BIBLIOGRAPHY OF ARTICLES RELEVANT TO PEG TREATMENT OF BASKETRY
* = Articles Ellen Carrlee had a copy
++ = Articles Dana Senge had a copy
Others are noted from their abstracts
* Alderson, Samantha. (2008) Posting to the American Institute for Conservation Objects Specialty Group discussion list 12/4/2008.
Ellen Carrlee’s notes: discussion of the changes to polyvinyl acetate resins of the AYA_ series, which are no longer the same ones trusted for many years made by Union Carbide. Conservation Support Systems and Talas still sell some of these resins made by a different manufacturer with some different specifications. Seems that Union Carbide stopped making them back around 2005?
++ Alonso-Olvera, Alejandra, Setsou Imazu, Demetrio Mendoza-Anaya, Andras Morgos and Ma. Teresa Tzompantzi-Reyes. (2002) “The Lactitol® Conservation of Wet Polychrome Wooden Objects Found in a 15th Century Aztec Archaeological Site in Mexico.” In ICOM Committee for Conservation, 13th Triennial Rio de Janeiro. Vol II. 2002. pp 712-717.
Dana Senge’s notes: Calculated moisture content—by drying samples in oven at 105º C for 48 hours. Weighed samples before and after drying- weight difference as percentage of dry weight gave moisture content. Determined artifacts low to intermediate degradation. Wanted to preserve chromatic surface of black and blue pigment. PEG modifies surface—excluded from testing. Tested sugar/alcohol, Lactitol® method. With Lactitol® method- biological attack can be avoided at low concentrations during impregnation. Lactitol 5-55% over 4 months- requires heat to reach 90% solubility. Lactitol®- 4-O(b-D- galactopyranosyl)-D-glucitol
* Astrup, E.E. “A Medieval Log House in Oslo – Conservation of Waterlogged Softwoods with Polyethylene Glycol.” (1994) Proceedings of the 5th ICOM Group on Wet Organic Archaeological Materials Conference, Portland, Maine. 16- 2- August 1993. pp 41-50
Ellen Carrlee’s Notes: Wood was identified as pine (Pinus silvestris) and spruce (Picea abies). For both highly degraded and less degraded softwoods, 50-55% PEG 4000 was most useful. She heated at 60C adding 10% every 8 weeks. She was getting 3-5 % shrinkage in the 50-55% range, but more above and below it. Waterlogged wood is already somewhat swollen, however. Results similar to Hoffmann’s 1990 article on softwoods. Wood with fairly intact cell wall structure might suffer from shrinkage with low mw PEG alone, perhaps the hygroscopic PEG pulls the water out of tyhe small spaces the molecule cannot fir into? Mentions that the two-step method is really intended for wood like oak that tends to have areas of both low and high degredation.
++ Barbour, R. J. (1983). The Hoko Alder: A Wood Technological Approach to the Conservation of Waterlogged Archaeological Wood. M.S. Thesis, University of Washington.
* Barbour, R.J. and L. Leney. (1982) “Shrinkage and Collapse in Waterlogged Archaeological Wood: Contribution III Hoko River Series.” In Proceedings of the ICOM Waterlogged Wood Working Group conference: Ottawa, 15-18 September 1981. pp. 209-225.
Ellen Carrlee’s notes: Shrinkage from capillary tension happens when the free water is pulled by evaporation from the void structure of the wood. Shrinkage is also caused from desorption of bound water from the cell wall. Article gives extensive info about which cells collapse in which direction.
* Baron, Maggie, Anne Wright. (1990) “The Conservation of Waterlogged Basketry Fragments from the William Salthouse.” AICCOM Bulletin Vol 16 No 3 1990. pp.85-92.
Ellen Carrlee’s notes: Ship sank 1841 Port Phillip Bay Australia. Excavated 1983. Willow, a diffuse porous hardwood, juvenile wood. Separately tested PEG 300 up to 10% and PEG 3350 up to 20% for a month. Seemed that high mw was more successful? Wonder why they didn’t try a two-step method.
* Bernick, Kathryn. Hidden Dimensions. WARP Occasional Paper 11, UBC Press. Vancouver: Canada. 1998
Ellen Carrlee’s Notes: Several useful articles, including Kaye & Cole-Hamilton, Bernick, and Johns mentioned in this bibliography.
* Bernick, Kathryn. “Stylistic Characteristics of Basketry from Coast Salish Area Wet Sites.” In Hidden Dimensions. WARP Occasional paper 11, UBC Press. Vancouver: CANADA. 1998
Ellen Carrlee’s Notes: Good resource for the things we ought to be noting in the Before Treatment condition reporting regarding the structure of the basketry.
++ Bernick, Kathryn. (1991) Wet Site Archaeology in the Lower Mainland Region of BC.
Dana Senge Notes: Excellent summary of sites, repositories, conservation and current condition of materials from wet sites in the BC. Specifics have been added to Sites table.
*++ Bilz, Malcolm, Tara Grant and Gregory S. Young. (1999) “Treating Waterlogged Basketry: A Study of Polyethylene Glycol Penetration Into the Inner Bark of Western Red Cedar.” Proceedings of the 7th ICOM Working Group on Wet Organic Archaeological Materials Grenoble 1998. pp.249-253
Ellen Carrlee’s notes: PEG 200 concentration over 20% but under 50% to give penetration to secondary wall without moist waxy surface. Cobalt thiocyanate in ether gives blue stain when it bonds with PEG, and inhibits autofluorescence of lignin. This study was with FRESH cedar bark samples, presumably because that would remove the obstacle of trying to examine degraded plant structures. Conclusions mention that archaeological samples need to be tested. I’m bothered by a foggy memory of seeing somewhere that lignin might have decreased fluorescence when the wood is very deteriorated?
Dana Senge Notes: Examination of extent PEG 200 penetrates cell walls in fresh western red cedar inner bark in aqueous solutions up to 20- 50% by volume. Cobalt thiocyanate in ether- when viewed in bright field—gives blue color only where PEG has been retained. Examined transverse sections. Test Results
20% PEG 200—dry and cupped due to shrinkage
30% PEG 200—dry, less cupped
40% PEG 200—moist, more flexible, flat
50% PEG 200—wax and moist
20% PEG 200 for 4 months and 20% PEG 200 for 12 months showed same level in impregnation
PEG 400- didn’t penetrate very well
Actual PEG concentration in basket sample lower than concentration in soln/bath— so 50% PEG 200 in solution is lower in sample. Freeze-drying above Eutectic can pose problems. Reducing amount of water in system that would actually freeze in freeze drying and sublimate. Higher then Eutectic would need to air dry. Examined 5% 3350- frozen and freeze-dried. Did not penetrate cell wall- did fill lumina. Cobalt thiocyanate stain caused 3350 to become liquid rather than crystalline
* Bilz, Malcolm, Lesley Dean, David W. Grattan, J. Clifford McCawley, and Leslie McMillen. (1994) “A Study of the Thermal Breakdown of Polyethylene Glycol.” Proceedings of the 5th ICOM Group on Wet Organic Archaeological Materials Conference. Portland, Maine. 1993. Ed Per Hoffmann.
Ellen Carrlee’s Notes: PEG from ten year old artifact did not decrease in molecular weight. Keeping oxygen or air out slows PEG degradation. Thermal aging increases PEG degradation. Slightly more degradation of PEG 3350 in presence of iron salts, but not so much with PEG 200. Less degradation of PEG 3350 in oak than by itself. BHA (not very soluble in water) helps reduce oxidation degradation of PEG 3350; propyl gallate does not, and also forms colored complexes with iron. No degradation of PEG with natural aging either in artifacts or by itself. Impregnation should take place at room temperature to avoid degradation. Store PEG at its most concentrated. PEG is reasonably reversible and can be leached from artifacts. Lower concentrations of PEG 400 (below 40%) oxidize more. In degradation, are we getting smaller molecules, do they go into the wood, or do they evaporate?
*Bilz, Malcolm; David W Grattan, Judith A Logan, Charlotte L. Newton. (1991) “An Investigation of Polyox for the Conservation of Wet Archaeological Textiles and Other Fragile Fibrous Materials. In Proceedings of the 4th ICOM Group on Wet Organic Archaeological materials Conference Bremerhaven August 20-24, 1990. Per Hoffmann, Editor. pp 189-208
Ellen Carrlee’s notes: POLYOX is a trade name for polyethylene oxides made by Union Carbide, ranging in MW from 100,000 to 8,000,000. PEGs are a lower MW homolog of POLYOX. They are stable and performed well in the testing, remain soluble in water, and give thin film consolidation to textiles without losing drape or becoming glossy. It has a high degree of wet tack and may feel slightly tacky after the treatment is done if held between the fingers for a few seconds. Application after freeze drying is better than before freeze drying. Mixing above 1% concentrations results in a substance that is difficult to work with.
* Bjordal, Charlotte and Thomas Nilsson “Decomposition of Waterlogged Archaeological Wood.” (2002) In Proceedings from the 8th ICOM Group on Wet OrganicArchaeological Materials Conference. Stockholm, 11-15 June 2001. pp.235-247
Ellen Carrlee’s notes: From the abstract…objects in near-anaerobic environments are soft and spongy with low density and high water content, caused by wood degrading erosion bacteria. Dimensions and surface details remain intact, since the bacteria can’t degrade all parts of wood cell wall. But more deterioration can occur when wetland is drained, since white rot is then able to work on the final degredation. Summary of methods to determine degree of degredation include measurements of density, measuring the maximum moisture content, chemical analysis to show decrease in cellulose content. In waterlogged environments, erosion bacteria are the main cause no matter what the pH, soil, fresh or saltwater. They are the only degraders active in anaerobic conditions. The S3 layer next to the lumen is the first attacked, then the S2 which has the most cellulose, and they leave behind a dark granular substance. Moderately degraded wood will show apparently sound tracheids next to heavily degraded cells. Lignin rich frame of the middle lamellae is left behind. Observation carried out with half polarized light, you may see a heterogenous pattern of totally degraded cells and sound ones making a black and white checked pattern. In the discussion afterwards: the slime material mixed with lignin and secondary degraders make it look under the microscope like there is still secondary cell wall, but it does not exist. Slime material does not wash out easily. Judy Logan mentions during the discussion that PEG is a wonderful plasticizer and can get between almost anything including to swell epoxies.
* Boone, R.S. and E.M. Wengert. (1998) “Guide for Using the Oven-Dry Method for Determining the Moisture Content of Wood.” Forestry Facts University of Wisconsin Dept of Forestry Ecology and Management No 89 June 1998.
Ellen Carrlee’s notes: %MC = amount of water in the wood (that is, original weight minus the oven dry weight) divided by the oven dry weight of the wood times 100. In oven drying, all of the water must be gone, but the wood must not be damaged. For best results, must used minimum of 100grams. From lumber, they should be 1” long along the grain and the full width of the thickness of the board. Weighing to 0.05g is recommended. Oven temperature empty should be 215-217F. Above may char and below may not remove all the moisture.Heat samples 18-24 hours. Method given for drying in a microwave oven with a rotating carousel to speed up the process : 200-360 watts (medium to low power) for up to 30 minutes for green wood. 10-12 minutes for dryer wood. Then the oven only takes 2-8 hours to fully dry the samples.
Borden, Charles E. (1976) “A Water-Saturated Site on the Southern Mainland Coast of British Columbia” The Excavation of Water-Saturated Archaeological Sites. National Museums of Canada.
Ellen Carrlee’s notes: Basketry 50% solution of PEG 1500 (Carbowax) for 21/2 to 4 months. This is the Musqueam site, DhRt4 dated 2970 +/- 90 BP.
*++ Brown, C.E. “(1991) Conservation of Waterlogged Wood: A Review.” In Waterfront Archaeology: Proceedings of the 3rd International Conference on Waterfront Archaeology. Held in Bristol 23-26 September 1988. pp 121-123
Dana Senge’s Notes: Sealed anaerobic deposits slow bacterial activity. Softer more soluble cellulose content is always depleted to some extent leaving behind harder structural substance—lignin. Conservation is physically bulking out lignin framework with hard materials. Treatment of composites—with metal components. PEG is acidic—aggressive towards metal. Recent research includes use of corrosion inhibitors and alkaline PEG-like substance? Summarizes Hoffman’s work (1981)—shorter molecular weights of PEG= good for treating lightly degraded woods, but too much has hygroscopic results. Larger longer MW bulks up lumina – good for badly degraded wood. Description of freeze-drying logic is very straightforward. Vacuum serves to make water vapor pressure on ice surface lower than the saturation vapor pressure in the ice. Latent heat source needed to replace energy lost by removal of water vapor. Description comes from Rosenqvist, 1975.
++ Brown, Margaret Kimball..(1974) “A Preservative Compound for Archaeological Material” in American Antiquity. Vol 39, Issue 3 July 1974. pp 469-473.
Dana Senge’s notes: Referenced by Grosso in treatment of cherry bark ties. Ethulose and PEG and Fungicide (ester of paraoxibenzoic acid) Used as reversible surface preservative in the field—“better than Elmer’s” PEG 1000- used for stone, bone, shell and pottery. PEG 400-fabrics Prep: Ethulose (3/4 ox) added to cold water gradually and stir. Add 4 parts PEG to 1 part Ethulose—stir until dissolved. PEG increased flexibility. In the field began applying as soon as skeletal material was brushed off to minimize differential drying between exposed and unexposed bone. Compound applied by spray or brush. Four applications average—each coat applied before the previous totally dry.
*++ Brownstein, Dr Allen. (1982) “The Chemistry of Polyethylene Glycol.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. p.279-287.
Dana Senge’s notes: PEG has waxed and waned in use—people keep coming back to reexamine its use. PEG is flexible polymer capable of random coiling with numerous folds and twists throughout the chain. Compact molecules—end to end distance proportional to square root of molecular weight. Solubility due to hydrogen bonding. Higher molecular weights possess polyether character. H-Bonding to ether oxygen atoms create solvent shell as opposed to monolayer. At T slightly above 100 degrees C- PEG’s become insoluble in water (rupturing H-bonds involved in complexation.) May conclude that size of complexation (between solvent and molecule would vary from solvent to solvent. Studies shown binding cations greater in methanol than in aqueous soln. PEG/Water complex larger due to greater numbers of bound water molecules. PEG/t-butanol complex—smallest of the three—structure of t-butanol severely limits number of bound t-butanol molecules. Complexing: with phenol, borax/boric acid? association reactions between PEG and Boric/Borates not observed. PEG- Phenol associations have been observed, similar to water. Brownstein raised—clathrate complex formed between Urea and PEG—creates hard solid that melts at 133 degrees C. Suggest that may strengthen degraded wood. Degradation of PEG- Fairly stable at acidic pH levels Thermal degradations accelerated with extreme pH. Pearson and MLF (pg 280) No one has studied long term effects of treating a soft degraded wood with PEG. Will hygroscopic nature of PEG attract moisture to wood? Resulting breakdown over long term? Brownstein response: Long Term degradation of PEG accelerated by heat, moisture content, air, possibly light certain decomposition products—corrosive toward badly degraded wood (formic acid) oxygen causes degradation. Decomposition can be detected by a darkening of color or by drop in solution viscosity and pH -degrades through random chain scission. -can use anti-oxidants to reduce degradation (0.05-0.10% concentration: p-methoxyphenol or phenothiazine, or food grade BHA (Butylated Hydroxy Anisole), BHT (Butyalated Hydroxy Toluene) or propyl gallate? want to minimize oxygen and UV exposure (UV degrades Lignin)–Trace metal ions may accelerate the decomposition of PEG hydroperoxides—Ferrous, Ferric and Cupric salts PEG does not support bacterial growth Discussion of Pre Treatment—to improve impregnation—various opinions include use of EDTA and acid.
++Bugni, Simone et al. (2008) “Evaluation of Conservation Treatments for Archaeological Waterlogged Wooden Artefacts” published online at http://www.ndt.net/article/art2008/papers/162Bugani.pdf, accessed in March 2009.
* Caple, Chris and Will Murray. (1994). “Characterization of a Waterlogged Charred Wood and Development of a Conservation Treatment.” Studies in Conservation. Vol. 39, No. 1 1994 pp 28-38.
Ellen Carrlee’s notes: PEG 4000 was used as a surface consolidant prior to lifting the “charcoal” some of which was waterlogged when excavated from a Neolithic site. Wood (oak) was thought to contain some of the original lignin. Various PEG treatments and consolidation were tested, including the use of PEG 400, PEG 4000, glycerol, Butvar B-98, Klucel G, Paraloid B-72, and epoxy. 10% PEG 400 followed by slow air drying over 40 days gave a good result for waterlogged samples. This left the char looking good but very fragile. The consolidants tested did not give satisfactory results, and the authors felt the most promising direction was PEG 400 and PEG 4000 in high concentrations.
* Carrlee, Ellen. (2005) “Conservation and Exhibit of an Archaeological Fish Trap.” In American Institute for Conservation Object Specialty Group Postprints. Vol. 13, 2005. pp 117-129.
Ellen Carrlee’s notes: Montana Creek Fish Trap was excavated in 1989-1991 dated 400-600 years BP. Made of spruce and hemlock wood elements and basketry-like spruce root lashings. Treatment notes are incomplete but suggest the trap was impregnated unheated for several months with 10% PEG 200, 5% PEG 1000 and 10% Carbowax Compound 20M, which seemed to be a PEG-like substance with molecular weight of 15,000 to 20,000g/mol. Due to its size, the trap was slowly air dried after impregnation. Spruce root was rather brittle after impregnation, small wads of Japanese tissue with wheat starch paste and a small amount of Jade 403 PVA emulsion were used to gap fill and adhere the loose root elements. Strips of Tyvek were adhered around the structure wooden elements in loose loops with Acryloid B-72. Paper describes mountmaking as well.
++Chen, Yuansheng, Yulin Xie, (2000) “A New Method for Treating Ancient Chinese Lacquer on Waterlogged Wood”. In Ostasiatische und Europäische Lacktechniken: internationale Tagung des Bayerischen Landesamtes für Denkmalpflege und des Deutschen Nationalkomitees von ICOMOS in Zusammenarbeit mit dem Tokyo National Research Institute of Cultural Properties, München, 11.-13. März 1999 pg 139-143.
* Clarke, Richard W. and Jane P. Squirrel. (1982) “A Theoretical and Comparative Study of Conservation Methods for Large Waterlogged Wooden Objects.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp. 19-27
Ellen Carrlee’s notes: 5 methods considered: 1) Dehydration and consolidation, involving treatments like acetone/rosin, alcohol/ether/rosin, dammar resin, Tetraethoxysilane, and dehydration with solvents. All of these aim to reduce the capillary tension issue of water leaving the wood and thus control shrinkage. Specialist equipment and large volumes of solvent count against these methods. 2) Freeze-drying to avoid the water phase. Pre-bulking probably needed, equipment for large items expensive. 3) resin impregnation and polymerization including methods with UV, gamma radiation, heat or catalysts. Concerns about safety and expense. 4) PEG to bulk as the most common method. Takes a long time but less expensive than many other methods. 5) Air drying, including slow drying in controlled humidities. Some evidence this works for things in good condition, very cheap.
*++ Cooke, Vincent, Deborah Cooke, and David W. Grattan. (1994) “Reversing Old PEG Treatments of Objects from the Ozette Site.” Proceedings from the 5th ICOM Group on Wet Organic Archaeological Materials Conference, Portland, Maine 16-20 August. 1993. pp 92-109
Dana Senge’s notes: Artifacts retrieved were more recent origin ~ 500 BP. 55,000 artifacts, 1.5 million faunal remains. Clay preserved these artifacts in anaerobic conditions. Not suffered fungal decay and little alteration of cell wall structure. In 1990 concerns about condition of pieces led to re-assessment. Describe collections as dark brown to black with layer of excess PEG on surface. Artifacts stable. 540 may not be entirely effective against cell collapse- but did prevent shrinkage and provided preservation. Some of the condition described above may be attributed to poor RH control and hygroscopic nature of PEG- Makah CRC has new storage area with new climate controls. Describe attempts to remove acetone rosin with acetone. (Rosin was probably colaphany according to Grosso article—but removal attempts didn’t include ethanol???) Basketry Fragment re-treatment (Small fragments (4×3 cm) A- removed/reduced PEG 540 in extraction bath of water with 0.1 sodium ortho phenyl phenate, Artifact became lighter in color. Frag freeze dried without PEG. Results: brittle and easily broken, but weave pattern clearly revealed. Consolidated with parylene C… fungal hyphae were not cleaned from surface and trapped by parylene leaving white deposit on surface. B- PEG extracted with 70% ethanol/water, Freeze dried (-20°C under vacuum) brittle and easily broken, consolidated with Polyox. Results: Wave patterns more easily discerned after Treatment- color improved. Superior in appearance to A but less strength. C-PEG extracted with 70% ethanol in water, freeze dried. No additional treatment Results: excellent in appearance, but brittle. 4th fragment extracted PEG with 70% ethanol. Cut into three separate sections. 1) freeze dried, 2) freeze dried, Polyox coat, 3) Freeze Dried, Paralyne C coated. Results—visually preferred 2, more realistic in texture and color. No examination of structure on microscopic lever or with SEM. Comments from discussion group on Cooke paper: Barbara Purdy- has used 540 successfully in past, not seeing excess and hygroscopic effects observed with Ozette pieces. Purdy was part of Ozette site from beginning. Grattan response—likely that location of museum is cause—light RH.. (however- Purdy works in Florida…high RH!) Some comments on experience with TEOS (Tera ethyl ortho silicate) none successful
Ellen Carrlee’s notes: Treated with PEG 540 blend c. 1973, hygroscopic, dark, heat used. Extracted PEG, retreated with 2-step PEG 200 at 15% for 40 days, and PEG 3350 at 9.5% for 20 days, then freeze dried. Acetone Rosin was found irreversible. They also consolidated with Polyox 2.5%. Discussion at end is very good…Grattan thought darkness of Ozette treatment was due to bulk treatment contaminants. Also, some hardwoods couldn’t take the osmotic effect of starting out with 50% PEG 540 blend and it caused some collapse. All agreed TEOS worked poorly.
* Cook, Clifford and David Grattan. (1991)“A Method of Calculating the Concentration of PEG for waterlogged Wood.” Proceedings of the 4th ICOM Group on Wet Organic Archaeological Materials. Bremerhaven 1990.
Ellen Carrlee’s notes: Liquid grade, such as PEG 200 is used to control cell wall shrinkage and waxy solid PEG 3350 is used to give some structural strength to the wood. Important to know:
Actual density of the wood
The normal density of undeteriorated wood
The Moisture content at the fiber saturation point of the undeteriorated wood.
These are the parameters used by PEGCON. Lower MW PEG such as PEG 200-600 penetrate into the cell wall better than higher MW. Higher MW PEG is meant to fill in the lumens and has been shown to work better on very deteriorated wood. Too much PEG 400 results in weeping , soft, humidity-sensitive wood.
Too much PEG 3350 results in heavy wood, harder to dry. Umax is the maximum moisture content, increases with deterioration. Some woods have a higher Umax naturally than others, so that’s why you have to know the species. Over 55% PEG mixture might not freeze in the drying process.
* Christensen, B. Brorson. (1970) The Conservation of Waterlogged Wood in the National Museum of Denmark. National Museum of Denmark, Copenhagen.
Ellen Carrlee’s notes: Includes history of treatments 1859-1962, and reports on work thusfar on Viking ships from Roskilde Fjord. Includes PEG 4000 in various solvents but having difficulty with the issue of oak penetration. Methylene chloride is the best solvent for removing PEG after treatment. Water is too slow and results in too much rubbing which obscures fine details and rounds sharp edges. Cold treatment with PEG 4000 as opposed to warm treatment resulted in less collapse of the oak. Began with 25% and increased to 50% for a year total
++Croes, Dale. R, John Fagan and Maureen N. Zehendner (ed). (2007) Testing the National Historic Landmark Wet Site 35MU4, The Sunken Village Archaeological Site, Multnomah County Oregon. Online publication: http://www.library.spscc.ctc.edu/electronicreserve/anth280/SunkenVillage/SVFieldReport2006.pdf, accessed: March 2009.
Dana Senge’s notes: Radiocarbon dates of site range from 130-600 years BP (1400-1870)
++Croes, Dale. R, John Fagan and Maureen N. Zehendner (ed). (2008). A U.S. “National Historic Landmark” wet site, The Sunken Village Site (35MU4), Portland, OR- The First Explorations. Synthsized 2006-2007 Field Season Report. Online publication: http://www.library.spscc.ctc.edu/electronicreserve/anth280/SunkenVillage/SVSynthesizedReport2007.pdf, accessed: March 2009.
Dana Senge’s notes: Discusses Lab methods: materials washed, tagged with metal ring tags (stainless steel specified in email communication with Dale Croes 3/22). Artifacts sewn into plastic screen/mesh bags, treated in 50/50 soln of water and PEG 400 for 4 months. Pgs 76/77
++Croes, Dale R, Rhonda Foster et al. (2005) Qwu?gwes – a Squaxin Island tribal heritage wet side, Puget Sound, USA. In Archaeology from the Wetlands: Recent Perspectives. In Proceedings of the 11th WARP Conference, Edinburgh 2005, ed. John Barber, Dr. Ciara Clark et al. WARP Occasional Paper 18. pg 135
++ Croes, D.R. (2001) North Coast Prehistory–Reflections from Northwest Coast Wet Site Research.” in, Jerome S. Cybulski, ed., Perspectives on Northern Northwest Coast Prehistory, Canadian Museum of Civilization, Hull, Quebec. Mercury Series Paper 60. 2001,
Dana Senge’s Notes: Summary of styles of baskets and materials found in PNW wet sites.
Croes, Dale R. (1976) “An Early Wet Site at the Mouth of the Hoko River” The Excavation of Water-Saturated Archaeological Sites. National Museums of Canada. 1976 pp.201-232
Ellen Carrlee’s notes: Initial excavation in 1967, artifacts treated with 50% solution of white glue. Summer 1973 excavations preserve at Ozette Project’s Neah Bay lab with Carbowax 1500 PEG, the same method applied to Ozette artifacts. Hoko is 45CA213. Dated 2210 +/- 70 and 2750 +/
++ Croes, Dale R. (1976) “The Excavation of Water-Saturated Archaeological Sites (Wet Sites) on the Northwest Coast of North America.” National Museum of Man Mercury Series, Archaeological Survey of Canada. Paper 50. National Museums of Canada, Ottawa. 1976.
Ellen Carrlee’s Notes: I have not yet seen this volume. Kathryn Bernick tells me that at the conference each presenter answered several questions, one of them about conservation treatments. All the papers are preliminary data and some details changed with further analysis. For about half the sites in this volume, Bernick says there has been no further analysis and reporting, and for most of the others it was only selected parts of the assemblages. Of the sites in the volume, comprehensive final site reports only exists for Hoko and Little Qualicum. Personal communication with Bernick, March 24, 2009.
Dana Senge: has taken extensive notes from this volume and compiled info into table of PNW sites, dates, treatments with condition notes as she is able to examine these collections.
++ Daugherty, Richard and Dale Croes. (1977?) “Wet Sites in the Pacific Northwest.” In Pacific Northwest Wet Site Wood Conservation Conference, September 19-22 1976 vol 1 pg 17.
Dana Senge’s notes: Discusses excavation technique developed using water spray from hoses to removed strata layer by layer. Mentions- Fishtown: a lot of sewage had been dumped into Skagit river, these artifacts were rich in organic materials which started to grow in lab before treatment. Musqueam- 3000 years old, treated fish nets (gill net). Hoko- Alternating clay and organic material layers. Ozette- 1967: first few basketry fragments were soaked in Elmer’s (produced stiff whitish looking basket) Understands that Elmer’s formula has changed and even more unsuitable than before. Also attempted field/excavation stabilization by brushing PEG onto objects
DeJong, J. (1978) “The Conservation of Shipwrecks.” ICOM Committee for Conservation 5th Triennial Meeting Zagreb 1978. 78/7/1.
* DeWitte, Eddy, Alfred Terfve, Jozef Vynckier. (1984) “The Consolidation of the Waterlogged Wood from the Gallo-Roman Boats of Pommeroeul.” Studies in Conservation Vol 20 no 2 1984. pp 77-83
Ellen Carrlee’s notes: PEG impregnation with PEG 4000 up to 85% heated to 65C in a steel tank. Oak with no solid core.
* Endo, Rie, Kaeko Kamei, Ikuho Iida, Yutaka Kawahara. (2008) “Dimensional Stability of Waterlogged Wood Treated with Hydrolyzed Feather Keratin.” Journal of Archaeological Science 35, 2008 pp 1240-1246.
Ellen Carrlee’s notes: Feathers have lower MW and cystine content than wool or other hair keratins. Waterlogged wood (oriental elm) with Umax 480% was treated with duck feather keratin and had a anti-shrink efficiency of 90 at the final concentration of no less than 30%. Generally the treatment does not go above 40% concentration. Duck feathers worked better than chicken or goose. Sttributed to higher crystalline index and stronger “anti-alkali” structures. Also effective with elm, oak, camphor, and magnolia. Mentions research by Kohdzuma et al 1996 that says Umax of waterlogged hardwood is higher than softwood and therefore treatment is more difficult. They used 10g feathers in 90mL of 1N sodium hydroxide to dissolve the feathers at 70C for 3 hours, then neutralized it with acetic acid. The sampels were immersed at 60C up to 40% with concentration raised every 3 days. Specimens were dried at ambient temp.
*Erling, Jo Ann. (1991) “Report: The Conservation of Artifacts from the Glenrose Cannery Site DgRr6. Archaeology and Outdoor research Branch. Ministry of Municipal Affairs, Recreation and Culture Province of British Columbia. March 1991 Unpublished.
Ellen Carrlee’s notes: The material is approximately 3500-4000 years BP and the cellular structure in the material was quite degraded, especially the basketry. PEG used was “ Carbowax 540 formerly Carbowax 1500” at 10-20% for six months, then freeze-dried for 5 days. This is described as the same treatment used on the artifacts from the Beachgrove Water Hazard Site DgRs30. For the Glenrose Cannery Basketry, an additional application or two of Rhoplex 33 was brushed on the surface in an effort to further stabilize them. It seems that descriptions of additional consolidation in the literature are often indicative of undertreatment with PEG. The report describes soaking objects (like wooden stakes) for extended periods to increase penetration, but I think the problem may have been not using high enough MW of PEG.
* Florian, Mary-Lou; Dale Paul Kronkright and Ruth E. Norton, (1990) The Conservation of Artifacts Made from Plant Materials. J. Paul Getty Trust.
Ellen Carrlee’s notes: Florian p.67: Western Red Cedar bark is secondary phloem tissue, takes place of true bark. Made of sheets of strong fibers. Includes sieve cells, parenchyma cells and phloem fibers (mechanical strength.) Pits are exaggerated when deteriorated.
*++ Florian, Mary-Lou and Richard Renshaw-Beauchamp. (1982) “Anomalous Wood Structure: A Reason for Failure of PEG in Freeze-Drying Treatments of Some Waterlogged Wood from the Ozette Site.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981 pp. 85-98
Dana Senge’s notes: Done at request of Milfie Howell, conservator at Neah Bay in 1979. Tested on non artifact wood samples from Ozette to determine if these treatments could be used for artifacts of comparable material. Standard PEG treatment had not been successful on a few small artifacts and thought freeze drying might be a good alternative… possibly help predict results PEG 540 Blend 50% for 6-8 months. Freeze drying and PEG Freeze drying treatments overcame majority dimensional changes- but not surface cracks. PEG/FD did eliminate more cracks than FD alone. Most important observation: inherent dimensional instability due to anomalous growth could not be overcome by treatment.
Ellen Carrlee’s notes: Factors that decrease the penetration of the PEG include:
Few and small hardwood cells
Inclusions (gum and tyloses) in hardwood vessels
Abundant hardwood thick walled fiber cells
Short soft wood longitudinal tracheids
Absence of ray tracheids
Absence of radial and longitudinal resin canals
Aspirated and encrusted bordered pits
Blind simple pits
High specific gravity
Ray parenchyma containing resin or extraneous material
Reduced tangential wall pitting
Extractives in heartwood
Picea sp. (spruces) and Thuja pliacata (Western red cedar) have no tangential permeability due to little tangential wall pitting, blind pits, and resin in the ray parenchyma cells. Spruce more permeable than red cedar due to resin canals and ray tracheids. Cedar is vulnerable to collapse of radial walls of the tracheids. In some woods, large thin-walled early wood tracheids adjacent to thick walled later wood tracheids can collapse and cause uneven grain appearance. In this case, spruce showed this result. Roots have many parenchyma cells and can have excessive longitudinal shrinkage. List of history-chemical tests given. Many softwoods samples show open enlarged tracheid bordered pits which make the wood abnormally porous.
Florian, Mary-Lou E. (1982) “Analyses of Different States of Deterioration of Terrestrial Waterlogged Wood – Conservation Implication of the Analyses.” Proceedings from the ICOM-CC Sixth Triennial Meeting Ottawa 1981.
Ellen Carrlee’s notes: Chemically altered lignin has increased solubility, prolonged PEG treatment might solubilize the lignin esp if the PEG is depolymerized. Bacteria attack softwood tracheids. Bordered pits show it. Variability of waterlogged wood is due to combination of: different states of deterioration, different species characteristics, different physical description of the artifact, and history of artifact prior to burial. Unlike cellulose, lignin is very persistent and can exist in normal amount in very very old wood. Lignin is the precursor of coal and oil (Breger 1952.) Lignin is soluble in alkaline solutions. (I guess it is good that PEG is a little bit acidic!) Brown rot fungi alter lignin to increase its alkaline solubility but soft rot fungi do not. Brown rot fungi selectively digest cellulose. White rot fungi selectively digest lignin. Good descriptions of microscopic appearance of these kinds of degradation.
* Florian, Mary-Lou. (1977) “Waterlogged Artifacts: the Nature of the Materials. Journal of the Canadian Conservation Institute.
Ellen Carrlee’s notes: In softwoods, most of the cells are tracheids, in hardwoods they are vessels and wood fibers. Bark of western red cedar is actually the dead outer phloem. Fibers have very thick walls. High lignin and tannin content, so survives when sieve cells and parenchyma cells destroyed. Very detailed description of the cells in cedar bark that is used for basketry.
Friedman, Janet P. (1978) Wood Identification by Microscopic Examination: A Guide for the Archaeologist on the Northwest Coast of North America. B.C. Provincial Museum, Heritage Record 5, Victoria B.C. 1978.
Ellen Carrlee’s Notes: I have not read this yet. Kathryn Bernick tells me it is based on the methods Friedman developed to identify species of wood artifact from Ozette. Wood only, not basketry, cordage, or bark. Only source that Bernick is aware of that deals with shrub wood. Personal communication with Bernick, March 24, 2009.
Giulminot, E., F. Dalard, C. Degigmy. (2000) “Electrochemical study of iron corrosion in various concentrations of polyethylene glycol (PEG 400) solutions”. Eur. Fed. Corros. Publ. 28, 2000 pp300-309.
Glastrup, Jens, Yvonne Sashoua; Helge Egsgaard, Martin Nordvig Mortensen. (2006) “Formic and Acetic Acids in Archaeological Wood. A Comparison Between the Vasa Warship, the Bremen Cog, The Oberlander Boat and the Danish Viking Ships.” Holzforschung. Vol 60 No 3. 2006.
Ellen Carrlee’s Notes: Solid-phase micro extraction (SPME) and gas chromatography-mass spectroscopy (GC-MS.) Content of formic acid relates to the content of PEG in the wood. Formic acid may be partly related to the PEG. Acetic acid is less in PEG treated wood than fresh wood. Acetic acid probably comes from the wood, and is age-dependent. Lowest in the 1000-year old wood tested.
* Grant, Tara and Malcolm Bilz. (1997) “Conservation of Waterlogged Cedar Basketry and Cordage.” Proceedings of the 6th ICOM Group on Wet Organic Archaeological Materials York, 1996.
Ellen Carrlee’s notes: Parylene coating on cedar “bark” baskets from Scowlitz site (500-1200 years old) treated with modified PEG treatment. 20% PEG 400 for 3 months and then freeze-dried. Came out still too fragile. Parylene is irreversible but worked well. Need a special vacuum pyrolysis chamber to apply it. NOTE: Bilz reported at the 11th ICOM-CC Triennial in Edinburgh Sept. 1996 that further study of Parylene shows that it does not age as well as they thought and it is not recommended for long term conservation. Also, personal communication with Kathryn Bernick (April 9, 2009) she mentions that the Scowlitz baskets are all made of cedar withes (wood splints) and not bark. Some of the cordage was indeed bark.
Grattan, David, Malcolm Bilz, Tara Grant and Judith Logan. (2006) “Outcome Determines Treatment: an Approach to the Treatment of Waterlogged Wood” Journal of Wetland Archaeology Vol 6 2006. pp.49-63.
Ellen Carrlee’s notes: describes methods used at CCI to determine and evaluate a treatment regime.
* Grattan, David. Cons Dist List posting 30 Aug 2000
Ellen Carrlee’s notes: Mallorytown wreck treated in 1967 with 20% PEG 1000 and 12.5% PEG 1450 by Parks Canada. Bremen Cog hull treated by Per Hoffman two-step PEG method now in Bremerhaven. If excess PEG is not used and the RH is kept below 60% treated artifacts do fine. Unstable sulphides in wood can oxidize to sulphates and eventually sulfuric acid, leading to destruction of the wood. PEG ages more slowly in wood than by itself. Lignin may act as anti-oxidant. PEG is chemically unlikely to cross link with the constituents of the wood.
* Grattan, D.W. and R.W. Clarke. (1987) “Conservation of Waterlogged Wood.” In, Conservation of Marine Archaeological Objects. Ed Colin Pearson. Butterworth. London and Boston. 164-206
Ellen Carrlee’s Notes: This is really the most comprehensive description of PEG use and especially its history, but of course it ends in 1987 AND this book is out of print and can be hard to come by. Unger, Schniewind, and Unger is also a good compilation and goes up to the year 2000. If PEG 3350 is too bulky to penetrate the cell wall, osmotic pressure could build and cause collapse. Microcapillaries in the cell wall thought to be around 10nm in deteriorated wood. Idea that bulking the cell wall without bulking the lumina has better results: less PEG oozes out, more natural appearance. Freeze drying gives a more even distribution of PEG. Grades of PEG over 600 need to be warmed in order to be completely dissolved, and the complete solubility of PEG in water is very important. Beginning impregnation with a low percentage of PEG is important to prevent osmotic collapse. Up to 30% PEG 400 is needed to bulk the cell wall. Freeze drying helps to keep it in there. Very deteriorated wood doesn’t have much cell wall and so the low mw PEG can’t stay in there as well. At the eutectic, PEG can’t freeze so you have a drying from with solid on one side and a mushy PEG solution on the other side.
*Grattan, David W.(1986) “International Comparative Study; Report” . ICOM Committee For Conservation Working Group on Wet Organic Archaeological Materials Newsletter. no 14. Feb 1986.
Ellen Carrlee’s Notes: I don’t remember seeing this published as a final thing elsewhere? Grattan described his work at CCI. He treated some samples with equal parts PEG 400 and PEG 3350 raised in 10% increments up to 30% v/v. Frozen at -40C and then freeze dried at -20C. results were good, but the very deteriorated samples should have had less 400 more 3350. Second batch placed in PEG 3350 in sequential batches of 10%, 20%, 30%m 40%, and 50% v/v and then freeze dried. Grattan feels the PEG reach the eutectic and did not freeze, so unfrozen PEG exuded onto the surfaces during freeze drying and some surface collapse.
*Grattan, David W. (1986) “Some Observations on the Conservation of Waterlogged Wooden Shipwrecks.” AICCM Vol. 12 No 3 and 4. 1986.
Ellen Carrlee’s Notes: Diagram of meniscus for water in a capillary, discussion of capillary tension induced collapse. Issue of PEG penetration into white oak timbers. Air pockets might prevent penetration. For more deteriorated wood, concentrations over 50% are better, and fill the lumens in addition to bulking the cell wall. Less deteriorated wood does all right with 10-30% which only bulks the cell wall. Capillary action during drying concentrates PEG at the surface and depletes the core…this can be overcome using concentration over 50%. (ellen: also, if you freeze, doesn’t ice crystal formation influence where the PEG ends up?) For humidity about 80% all PEGs are affected. Lower concentrations of PEG can be used with freeze drying than with air drying.
* Grattan, David W.(1982) “A Practical Comparative Study of Several Treatments for Waterlogged Wood” Studies in Conservation Vol 27 No 3 Aug 1982 pp 124-136
Ellen Carrlee’s notes: Water content is a rough guide to the state of deterioration. For smaller sample, no advantage to heating the PEG 400. Didn’t help with penetration, shrinkage or cracking, but it did make end result darker. In larger objects, heat may speed up the diffusion. PEG 400 can end up soapy and attract dust. Can melt some PEG 4000 on surface to make it stronger and less absorbent. PEG 540 is a 50/50 blend og 300 and 1540 MW ave of 500-600…tends to creep out of the wood, looks heavy, dark, waxy. Can be introduced unheated and unstirred in 10% increments over 18months. Final concentration 64% v/v.
* Grattan, David. (1982) “A Practical Comparative Study of Treatments for Waterlogged Wood part II The Effect of Humidity on Waterlogged Wood.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp. 243-252.
Ellen Carrlee’s notes: Wood treated with low MW PEG (400 or 540 blend) should not be exposed to RH above 60%. Below that shouldn’t matter.
* Grattan, David W. (1980) “ Consolidants for Degraded and Damaged Wood” in Proceedings of the Furniture and Wooden Objects Symposium: 2-3 July 1980. Ottawa, Ontario. Pp. 27- 42
Ellen Carrlee’s notes: CCI testing of resins for consolidation of dry and degraded wood (not PEG treated) : Acryloid B 66, 67, 72, 82; Elvacite 2013, 2044, 2045, and 2046; Polyvinyl acetates AYAA, AYAC, and AYAF; polyvinyl butyrals butvar B72, 76, 98; Union Carbide’s XYHL, and Mowital B30H, B60H, soluble nylon, and Xylamon. One of the better description of cautions for in situ polymerization: Vacuum chamber limits size and is expensive, heat is generated, time for impregnation is limited, monomer tends to drip out, wood may contain quinines or phenols that can impede the path of polymerization. Problems with epoxy: no short term reversibility, first application determines final extent of penetration, mistakes are final, heat up top 75C is generated, poor appearance (dark). Both insitu polymerization and epoxy have an inherent lack of control. Grattan provides a nice list of desirable characteristics: good adhesive, strength to surface and/or structure, flexible but hard, not creep, high concentration with low viscosity, simple application, non toxic, not yellow, short term reversibility, maintain mechanical properties. He lists AYAA, AYAF and AYAC as having unsatisfactory Tg and therefore risking creep. PVB’s have very good combo of high tensile strength, hardness and elongation of break. Butvar B-98 has a lower viscosity than many PVBs. Acrylics generally have the lowest viscosity. PVBs may chalk on drying if applied in pure ethanol, esp if it has traces of water. 5% t-butanol to the solvent helps avoid it. His frist choice was polyvinyl butyrals, then acryloids B72 and B67 and third AYAC and soluble nylon.
++ Grosso, Gerald (1978) “After Excavation, Then What” in Society for California Archaeology Occasional Papers in Method and Theory in California Archaeology. 1978. Pg 53-56
Dana Senge’s notes: Discusses the need for conservation considerations even at dry sites. No cookbook method can be applied. Consider variations of environments from which something was removed and where it will be placed. Practice of conservation: Continuing in experimental character and admission that we don’t have all the answers.
++ Grosso, Gerald. (1975?) “Field Conservation of a Variety of Waterlogged Artifacts from a Remote Archaeological Site” in Conservation in Archaeology and the Applied Arts: preprints of the contributions to the Stockholm Congress, 2-6 June 1975. pg 250-253
Dana Senge’s Notes: Studied Seborg and Inveratity publications. Science article (see below) Conservation of 200 Year Old Waterlogged Boat with Polyethylene Glycol:Studies in Conservation 7 (1962) 111-119 The conservation of Wood from Fresh Water and Treating Wood with PEG. (Both from Diving into the Past, proceedings of a conference on Underwater archaeology. Minnesota Historical Society 1963. Experimented (haven’t found full details yet) Artifacts from vegetable origin were treated with 50% PEG Carbowax 1500 (later known as 540). Water treated with Cytox 2013 biocide (100 ppm) Treated 95% of 18,000 artifacts this way 5% wouldn’t accept PEG treatment—oil impregnated hardwoods?
++ Grosso, Gerald. (1976) “Volume Processing of Waterlogged Wood at a Remote Archaeological Site: Modification of old Techniques, Identification of Special Problems and Hopes for Their Solution”. In Pacific Northwest Wet Site Wood Conservation Conference, September 19-22. 1976 volume 1 Neah Bay. WA.
Dana Senge’s Notes: Summary of site location and challenges of field conservation. Started testing after 1967 season: inspiried by Barkman (Wasa) Seborg and Inverarity. Samples of Various grades of PEG from Union Carbide. Tested on waterlogged wood. Build Field Lab for initial processing. Lab at Neah Bay opened in 1971. Tested three types of PEG Carbowax 600, 1000, 1500 (name change reported in July 1976 paper—1500 became 540 and 1540 became 1500. Tests on waterlogged wood- piece divided into four parts. Test samples were placed into test PEG Baths: 30% 600 in H2O, 30% 1000 in H2O, 30% 1500 (540) in H2O, 4th sample was allowed to air dry. After 60 days each sample had sunk to bottom of test tank. These were allowed to dwell for an additional 30 days to increase impregnation. Mentions further tests made in 1970 on cedar bark basketry and other fragments. Tests included: Application by hand of various grade. Variables included: solvents, concentration of PEG, temperature and times. Solvents: H2O, EtOH, MeOH, Isopropanol. Concentrations: 10-50% graduation, direct immersion into 50%, direct immersion into 100%. Temperature ranged from ambient T (45-65°F) to 140° F Times- from topical application once a day for 5 days to continued soaking for 60 days. Considering results compared with cost, safety, efficacy and labor- developed a standard technique of 50% 540 in water for 30 days at ambient T. This stabilizes basketry, cordage, matting and solid wood artifacts up to an inch thick (cross section). Thicker requires increased immersion time. Artifacts stored in unheated building with RH fluctuations 40-85% Observed ‘hygroscopic nature of PEG’ (possibly observed seeping/weeping)? Problems: Some artifacts resistant to PEG Treatment. After many tests: concludes some things will be preserved with little regard to concentration. While some things are unstable regardless of adjusting any variable (concentration, time, temp of PEG treatment). These artifacts appeared to be mostly hardwoods, most common feature: impreg with oil (hand, seal or food oils) Possibly crosslinking of oils making difficult to remove and then PEG treat. Attempted several treatment solutions included HCL soak pre-PEG. Refers to Bertrand (ship with tools brought up from river. Alternative Treatments— Acetone Rosin Impregnation discussed by McKerrel, Roger and Varsnyi. Found difficult to get rosin. Appears to have treated with PEG first, then allowed to dry, then acetone rosin impregnation? Ethulose/PEG treatment: for wild Cherry Bark bindings (didn’t stabilize with PEG, tended to shrink around object until breakage occurred) 20% Ethulose 100 in 1000ml of water, stirring 30 min then adding 100g PEG, stirring until dissolved. Also used for assembling Shattered artifacts- solutions applied by medicine dropper or hypodermic needle and syringe. Found that this mixture with PEG 4000 works best with basketry containing split limb elements. Mixture using 540 blend more suited for bark elements.
*Halfors, Birgitta. (1994) “Improvements of the Conservation Programme for Tank Treatment with Polyethylene Glycol at the Vasa Conservation Laboratory.” Proceedings of the Fifth ICOM Group on Wet Organic Archaeological Materials, Portland, Maine 16-20 August 1993. pp51-62
Ellen Carrlee’s notes: Tank treatments of the wooden Vasa material began in 1962. Early approach used increased increments at the end, but the later treatments used larger increments at the beginning and smaller ones towards the end. I had trouble making sense out of the abstract, have not yet reviewed the article
* Hamilton, Donny L. (1998) Methods of Conserving Archaeological Material from Underwater Sites. Nautical Archaeology Program Department of Anthropology Texas A&M University.
Ellen Carrlee’s notes: Amount of water in waterlogged wood is calculated: weight of wet wood minus weight of oven dried wood divided by weight of the oven dried wood and multiplied by 100 to give % water. Anything over 200% is considered degraded. Explanations of other treatments for waterlogged wood are also given.
Hawley, Janet K. (1989) “Conservation of Waterlogged Rope from a 16th C. Basque Whaling Ship” Conservation of Wet Wood and Metal, ICOM-CC Working Group on Wet Organic Archaeological Material and Metals Fremantle 1987
Ellen Carrlee’s notes: Ship sank in 1565, Three most successful treatments, first one used most extensively:
1% Ethulose 400, 5% PEG 400, 2% glycerol in water
2% Ethulose 400, 10% PEG 400 and 2% glycerol in water
22% polyvinyl acetate emulsion, 10% PEG 400 in water
Hoffmann, Per, Adya Singh, Yoon Soo Kim, Seung Gon Wi, Ik-Joo Kim, Uwe Schmitt. (2004) “The Bremen Cog of 1380: An Electron Microscopic Study of it Degraded Wood Before and After Stabilization.” In Holzforschung Vol 58 No 3 2004 pp 211-218
Ellen Carrlee’s notes: Two-step PEG treatment for wood degraded primarily by erosion bacteria. SEM/TEM investigation. In degraded tissues, all cell types were filled with PEG 3000. Non-degraded tissues are impermeable to PEG 3000 and impregnated only with PEG 200. Confirms that PEG 200 goes into the cell walls.
Hoffmann, Per. (2003?) “The Bremen Cog Project: the Conservation of a Big Medieval Ship” In ICOM-CC 13 Triennial Meeting Rio De Janiero 22-27 Sept 2002. pp718-723
Ellen Carrlee’s Notes: Ship treatment took 19 years, was rebuilt before the PEG treatment. Two-step treatment on a large scale.
Hoffmann, Per. (2002) “The Conservation of the Bremen Cog: the Final Years” Proceedings of the 8th ICOM Group on Wet Organic Archaeological Materials. Stockholm 11-15 June 2001. pp 27-48
Hoffmann, Per. (1997) “The Conservation of the Bremen Cog: Between the Steps.” Proceedings of the 6th ICOM group on Wet Organic Archaeological Materials. York 9-13 Sept. 1996. pp 527-543.
Ellen Carrlee’s notes: PEG 200 and then PEG 3000 as a two-step process. First impregnation of PEG 200 took 10 years due to funding. Can reduce the amount of PEG you need by putting salt water filled displacement units all around the boat in the tank. 63% PEG 3000 was used. At publication, there were still 2-3 years projects for the second step to be completed.
++Hoffmann, Per. (1993) “Restoring Deformed Fine Medieval Turned Woodware”. In ICOM Committee for Conservation tenth triennial meeting, Washington, DC, 22-27 August 1993: preprints. pp 257-261.
Dana Senge’s Notes: Retreatment of dried misshapen wooden artifacts with PEG.
* Hoffman, Per. “On the Stabilization of Waterlogged Softwoods with Polyethylene Glycol (PEG). Four species from China and Korea.” Holzforschung. Vol. 44 No 2. 1990. pp 87-93.
Ellen Carrlee’s notes: Best stabilization of degraded softwoods is 50% PEG4000 with cross section shrinkage of only 2-4%. Chinese Red Pine Pinus massoniana, Pinus densiflora, Chinese Fir Cunninghamia lanceolata, and Cryptomeria japonica treated with PEG 400 and PEG 4000. All species responded the same. Best stabilizations with 20% PEG 400 and 50% PEG 4000. Using higher concentrations for softwoods is not effective. PEG 4000 cannot penetrate cell wall but can extract water from it. PEG contracts 7% on setting. Vasa used molten PEG 6000 on the surface, but it is a hard and shiny lacquer.
* Hoffmann, Per. (1986) “On the Stabilization of Waterlogged Oakwood with PEG II Designing a Two-Step Treatment for Multi-Quality Timbers.” Studies in Conservation 31, 1986 pp.103-113
Ellen Carrlee’s notes: Bremen Cog PEG 200 and then PEG 3000. Two step for thicker woods with outer layer of degraded wood and a core of less degraded wood like oak and pine. Can even do simple air drying afterwards. Results with intermediate MW not as good as two step. PEG 200 stabilizes slightly degraded wood better than PEG 300. Maybe some lower MW PEG diffuses out during the second step, but some is trapped or adsorbed in the capillaries. Doesn’t weep until RH is 86%. Can be air dried, too big for a freeze dryer.
* Hoffmann, Per. (1985) “On the Stabilization of Waterlogged Oak with PEG – Molecular Size Versus Degree of Degradation.” Waterlogged Wood Study and Conservation, Proceedings of the 2nd ICOM Waterlogged Wood Working Group Conference, Grenoble, France. 28-31 August? 1984. pp. 243-252.
Ellen Carrlee’s notes: More degraded oak does better with PEG 3350, while less degraded does better with PEG 200. PEG 1450 is poorer for both. A 2-step method is more effective. For a long time people were afraid to use anything under PEG 1500 for fear it would be too hygroscopic.
++ Hoyle, Robert J. (1977?) “Relating Wood Science and Technology to the Conservator” In Pacific Northwest Wet Site Wood Conservation Conference, September 19-22 1976 vol 2 pp 99.
Dana Senge’s notes: Driest atmospheres—in equilibrium with wood about 5% moisture content. Indoor environments rarely produce moisture contents above 10-12% Shrinkage observed from fully saturated to dry 3.5-10% dependent upon species. Western red cedar on low end of scale. Artifacts from waterlogged sites in swollen condition- larger than they wood be in use (5-10% larger than in use). When we preserve with PEG we preserve at larger size not “normal use size”… (just as I suspected!) Anatomies of bark and wood are different. Considerable amount of literature on bark- anatomy, chemistry, resin. Includes great bibliography with paper
++Jakes, K.A. and L.R. Sibley. (1983) “Survival of Cellulosic Fibres in the Archaeological Context.” In Science and Archaeology. No. 25, pg 31-38. 1983.
* Jeberien, Alexandra and Malcolm Bilz. (2000) “Comparison of Air Dried and Freeze Dried Solutions of Polyethylene Glycol 3350” In ICOM WOAM Newsletter No. 31 June 2000.
Ellen Carrlee’s notes: They expected all to line the walls and bottom of beakers. Air dried samples had consistency of beeswax and occupied only the bottom the beaker, might have lined walls if they were more porous? Freeze dried samples had a powdery matrix appearance and occupied the full volume that the frozen water/PEG mix had originally occupied. For the freeze-dried, when they were returned to low temperature, higher concentrations that had been freeze-dried (20% and above) showed some concentrated PEG solution at the bottom of the beaker that had not been able to get past plugs of PEG. 5% did not have that, so water must have escaped.
*++ Jensen, Poul; Grethe Jorgensen, Ulrich Schnell. (2002) “Dynamic LV-SEM Analyses of Freeze Drying Processes for Waterlogged Wood” Proceedings of the 8th ICOM Group on Wet Organic Archaeological Materials Conference, Stockholm, 11-15 June 2001 pp.319-333
Ellen Carrlee’s Notes: Looking at distribution of PEG in wood with Low Vacuum Scanning Electron Microscopy (can avoid sputter-coating of SEM and the bias it introduces.) Machine itself acts like a freeze-dryer with wet samples. Phase diagrams for PEG done by different authors usually don’t agree, but they all agree the eutectic is around 55% (w/w) for all the mw of PEG. Eutectic temperatures are not in agreement. Below the eutectic temperature, a solid lamellar eutectic phase forms between the ice crystals. Phase diagram they suggest for PEG 6000 shows solid PEG as well as a solid PEG/ice mixture at freezing temperatures with a concentration above 55% (eutectic.) Below the eutectic, all PEG solutions result in 3-9% expansion at temps below freezing. Ice has 9% expansion, PEG has 7% volumetric contraction. Is this a primary function of the PEG? PEG solutions below 55% all expand on solidifying. PEG concentrated in the later wood and distributed irregularly in the early wood. Collapse can be avoided if we stay below the eutectic temperature. When ice forms, the PEG gets more concentrated. Formation of large ice crystals contributes to uneven distribution of PEG. Even distribution of PEG is only possible for eutectic concentrations. PEG has a low affinity for the secondary cell wall (Jensen’s PhD thesis from 1995.) Heating after freeze drying causes the PEG to aggregate on surfaces of cell wall and give better distribution. They suggest investigating methods to nucleate smaller ice crystals and thus better distribution.
Dana Senge’s Notes: Water will not freeze at normal freezing T. Aqueous solutions of water-soluble agents like PEG hygroscopically bound to water. Suggests that the only way to have even distribution of PEG with freeze drying process is to hit eutectic. All other concentrations will consist of pockets of mixtures: eutectic, ice crystals or solid PEG. Ice crystals or solid PEG are larger than diameter of cells—leave voids in laminar structure. Also “the 9% expansion of ice crystals are only partially counter balanced by 7% volumetric contraction of PEG.” Also—only tested single step impreg. System—not two step system
* Jenssen, Victoria and Lorne Murdock. (1982) “Review of the Conservation of Machault Ships Timbers: 1973-1981” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp. 41-49
Ellen Carrlee’s notes: Mostly oak, preserved in anoxic silt in shallow brackish tidal area. Initial treatment to try slow drying by burial in wet sand. After five years, they didn’t seem to be drying out, plus sand was contaminated with sodium chlorophenate. Treatment 2 was spraying the timbers for two years, intermittently, with PEG 540 15% because 25% didn’t seem to soak into the wood.Treatment 3 was applying thick PEG 540 directly to the timbers every 6 months, and this was absorbed very quickly in room at 18C and 80% RH. Treatment 4 had not yet happened when this was published, they were aiming for display by 1984.
*++ Johns, Dilys A. (1998) “Observations Resulting from the Treatments of Waterlogged Wood Bowls in Aoteroa (New Zealand) in Hidden Dimensions WARP Occasional Paper 11, UBC Press. Vancouver: Canada. pg 317.
Dana Senge’s notes: Two forms of treatment used at University of Aukland. Before 1986: one step impregnation with incrementally increasing concentrations of aquaeous PEG 3350 followed with freeze drying from 5-40% over 6-12 months followed with freeze drying. After 1986: two step process pretreated with PEG 400 than 3350. Conservators were forced to try slow air drying in 1987 following PEG treatment (pieces too big for freeze drying)—had good results. Felt that they could halt air drying and continue impregnation if needed. PEG shrinks in freezing—thought to counteract expansion of freezing water.
Ellen Carrlee’s notes: Supports other literature (Hoffmann ) that indicate the two-step PEG method is better for wood that includes both sound and deteriorated areas.
* Jover, Anna. (1994) “The Application of PEG 4000 for the Preservation of Palaeolithic Wood Artifacts.” Studies in Conservation, Vol. 39, No. 3 pp 143-165.
Ellen Carrlee’s notes: Charred wood from 45,000 years BP, pinus sylvestris and juniperus. 80% solution of PEG 4000 at 100C was used.
* Kaenel, Gilbert. (1994) “PEG Conservation of a Gallo-Roman Barge from Yverdon-les-Baines (Canton of Vaud, Switzerland.)” Proceedings of the Fifth ICOM Waterlogged Archaeological Materials Conference. Portland, Maine 16-20 August 1993. pp. 143-165.
Ellen Carrlee’s notes: Mostly oak, treated in a tank with PEG 4000 raised from 15% to 85% at 60C over 18months of impregnation. AD 400. Slow drying, natural looking finish reported.
++Karchut, Jeremy. (2008) “Spruce Root Collecting at Fish Bay” website: http://www.fs.fed.us/r10/ro/sd_notes/summer_07/spruce_root/spruce_root.shtml , accessed November 2008.
Dana Senge’s notes: Describes experience gathering materials and preparing them for weaving with Teri Rofkar, Tlingit weaver.
*++ Kaye, Barry and David J. Cole-Hamilton (1998) “Supercritical Drying of Waterlogged Archaeological Wood” in Hidden Dimensions . pg 329.
Dana Senge’s notes: Supercritical carbon dioxide used for drying process. Shrinkage is a little greater than freeze drying. Good for composite objects that can’t be treated with PEG or materials that resist PEG treatment. One example—hemp rope was very brittle requiring additional consolidation
Ellen Carrlee’s notes: Only 3 methods to remove the water: air dry, freeze dry, and supercritical dry. Air dry has liquid turn to gas, but liquid vapor surface moves through the object and may cause damage. Freeze dry turns the liquid to a solid and then with low temp and pressure the solid goes to a gas through sublimation, but cryprotectants needed because of the 8% volumetric expansion of water as it turns into ice. Supercritical drying goes from liquid to gas without crossing liquid-gas boundary using the supercritical region where distinction between gas and liquid ceases to apply. Need to replace water with a solvent (methanol, risk of soluble components) then replace the solvent with high pressure liquid carbon dioxide, and then heat it until it goes beyond the critical point. Equipment and chemical intensive (need an autoclave). Temps range from -78C to 50C during treatment. Compression/decompression risks. Lighter color, poor tolerance to changes in environment, poor mechanical properties in some cases.
* Keene, Suzanne. (1982) “Waterlogged Wood from the City of London.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981 pp. 177-180
Ellen Carrlee’s notes: Variety of different hardwoods and softwoods. PEG 4000 was use up to 90% at 50-60C, but wood came out dry and splintery so they switched to PEG 1500. Rinsed with hot water, wrapped in towels and dried slowly in the dark. Objects come out heavy, brittle, but not much shrinkage. A little darker, and fine detail is preserved. For freeze drying, PEG 400 left the wood too fragile, 40-50% PEG 1500 or 4000 worked better. She’s down on acetone/rosin because while other colleagues have had luck with metal handled tools, she’s not had the best luck and working with hot acetone is difficult.
Lindblad, Cecilia and Ingmar Persson. “Polyethylene Glycol/ Polyethylene Oxide: An Overview of the Physical-Chemical Properties of PEG/PEO” Presented at the ICOM-CC Working Group on Wet Organic Archaeological Materials Amsterdam,10-15 Sept. 2007. Not yet published.
Ellen Carrlee’s notes: Persson generously sent me a copy. Describes a lot of chemistry of the polymer. There’s no clear distinction between PEG/PEO. PEG extremely soluble in water, but solubility of PEO actually decreases with high temps, salt, and strong stirring. Exponential increase in viscosity with higher molecular weight. Bonding discussed. Hydration radius for PEG 4000 at 30C is 50 nm. High mw PEGs above PEG 1000 form random coils and low mw PEGS below PEG 600 maybe form stretched aggregate chains? PEG on objects treated with high temps show signs of decomposition.
MacLeod, Ian D. (1990) “Conservation of Waterlogged Timbers from the Batavia 1629.” The Bulletin of the Australian Institute for Maritime Archaeology. Vol 14 No 2 1990 pp1-8
++ Martin, Robert and John B. Christ. (1970) “Elements of bark structure and terminology” in Wood and Fiber. Vol 2, no. 3, pg 269-279. 1970.
Dana Senge’s notes: Inner bark: physiologically active tissues between the cambium and the last formed periderm=phloem. Outer bark: layer of dead tissue-outside the last formed periderm—rhytidome.
* Masuzawa, Fumitake, Makiko Okuni. (2002) “Study on Change of PEG Impregnated Waterlogged Wood over Twenty-Eight Years.” In Proceedings from the 8th ICOM Group on Wet OrganicArchaeological Materials Conference. Stockholm, 11-15 June 2001 pp. 606-607.
Ellen Carrlee’s notes: Humidity in Nara where these artifacts are is high in the summer. Waterlogged oak with water content 660% treated with PEG 1500blend, 2000, 4000, and 4000S. Concentrations were 20%, 40%, 60% and 80% as well as molten at 100%. PEG 4000 in solution (not the molten) performed the best.
++Masuzawa, Fumitake; Ueda, Naomi; Inoue, Michiko; Kawamoto, Kozo. (1999) “Screening Some Methods for Conserving and Restoring about 500 Objects of Waterlogged Japan ware” Proceeding of the 7th ICOM-CC Working Group on Wet Organic Archaeological Materials Conference, Grenoble, France 1998. pg 268-274.
Dana Senge’s notes: Treatment of Urushi objects (mostly bowls and plates)
Earliest 1957: coat with acrylic resin, no records, artifacts not highly damaged/degraded.
1970’s: soaking objects in 20% PEG 4000 and concentrations up to 100%. Useful on objects with urushi layer in good condition, thin urushi layer would start coming off, peeling into pieces due to heated and concentrated PEG.
1980’s (early): Alcohol-xylene-resin. 1) start by replacing water with ethanol, 2) then xylenes 3) then xylenes, rosin and damar. Not heated, but thin low urushi layers still peeled and curled when replacing water with alcohol. Drying oils in Urushi and charcoal powder in ground damaged by heat and org. solvents in these processes.
1991: freeze drying, tested concentration of PEG 4000 and cooling rate/temp.
tests: Impregnation 20% PEG 4000 (2 weeks) Impregnation 40% PEG 4000 (4 weeks) Prefreeze, then 2 week Freeze Dry. Impregnation short—to have little effect on urushi.
Masuzawa, Fumitake. (1973?) “Experiments on the Impregnation of Waterlogged Wood with PEG Part I” Conservation Science Bulletin. Hozon Kagaku Kentyushitsu Kiyo. Vol. 2 1973? pp5-11
Ellen Carrlee’s notes: this is from a literature review in ICOM-CC WOAM Newsletter No 8 Nov 1982. Samples of waterlogged oak with 650% water content pre-treated with EDTA and then 20%, 40%, 60% and 100% PEG 3300, 2000, and 540 blend at 60C for 21 days. Impregnation incomplete. PEG 540 blend continued to ooze out, and PEG 3300 and PEG 2000 caused darkening.
Masuzawa, Fumitake and Yoichi Nishiyama. (1974) “Experiments on the Impregnation of Waterlogged Wood with PEG Part II” Conservation Science Bulletin. Hozon Kagaku Kentyushitsu Kiyo. Vol. 3 1974 pp39-46
Ellen Carrlee’s notes: this is from a literature review in ICOM-CC WOAM Newsletter No 8 Nov 1982. Size greatly affects time for saturation: 50-60 days for 3cm wood, but more than 120 days for oak of 7.5cm
Masuzawa, Fumitake and Matsuda Takatougin. (1974) “Surface Treatment for the Removal of Dark Hue on Waterlogged Wood Impregnated with PEG.” Conservation Science Bulletin. Hozon Kagaku Kentyushitsu Kiyo. Vol. 3 1974 pp 47-51
Ellen Carrlee’s notes: this is from a literature review in ICOM-CC WOAM Newsletter No 8 Nov 1982. Swathing the wood in cotton bandages soaked in ethanol.
Masuzawa, Fumitake. (1974) “Change of Waterlogged Wood Impregnated with PEG Along the Lapse of Time.” Conservation Science Bulletin. Hozon Kagaku Kentyushitsu Kiyo. Vol. 3 1974 pp. 52-58
Ellen Carrlee’s notes: this is from a literature review in ICOM-CC WOAM Newsletter No 8 Nov 1982. Reviewing wood treated with PEG after one year. Wood treated with PEG 540 blend absorbed moisture, oozed out and there was shrinkage. PEG 2000 showed radial cracks after 3 months and some expansion. PEG 3300 showed no great change. Based on other articles, they were probably looking at oak.
* McCawley, J.C. (1977) “Waterlogged Artifacts: The Challenge to Conservation.” In Journal of the Canadian Conservation Institute. Vol 2, 1977. pp17-26.
Ellen Carrlee’s notes: Good description about waterlogging on the cellular level. Many older treatment methods described.
*++McCawley, J.C., David Grattan, Clifford Cook. (1982) “Some Experiments in Freeze-Drying: Design and Testing of a Non-Vacuum, Freeze Dryer” in Proceedings of the ICOM Waterlogged Wood Working Group Conference. Ottawa 15-18 September 1981. pg 253-262.
++ McKerrell, H, E. Roger and A Varsanyi. (1972) “The Acetone/Rosin Method for Conservation of Waterlogged Wood.” In Studies in Conservation Volume 17, 1972. pg 111-125.
Dana Senge’s notes: Grosso used this procedure with some pieces at Ozette that were not stabilized with PEG Treatment. Heartwood of Oak—very little deterioration after thousands of years. Compared treatment to standard PEG 4000, 20% in water. Procedure: Initial treatment with dilute 3-5% HCL followed by thorough washing. Dehydrate the wood – immersion in three baths of acetone over a period of two weeks. Impregnation with rosin (colophony) saturated acetone @ 52 degrees C followed by evaporation of solvent. (rosin 67% w/w of liquid.
* McConnachie, Glenn; Rod Eaton and Mark Jones. (2008) “A Re-Evaluation of the Use of Maximum Moisture Content Data for Assessing the Condition of Waterlogged Archaeological Wood.” E-Preservation Science, Morana RTD 2008.
Ellen Carrlee’s notes: took maximum moisture content (Umax) profiles from oak, poplar, and pine and compared it to visible degradation patterns for timbers that have a more degraded surface and more solid core. Took Umax modern plus 50% to come up with limit for what is to be considered degraded: oak is 150%, poplar 400% and Scots pine 250%. Conservators typically assess timbers by probing, taking core samples and getting Umax from fragments.
*Mitchell, H.L. (1972) “How PEG Helps the Hobbyist Who Works With Wood. “ US Dept of Agriculture Forest Service Forest Products Laboratory, Madison Wisonsin.
Ellen Carrlee’s Notes: Interesting info on what adhesives are recommended with PEG
++ Morgos, Andras and Setsuo Imazu. (1994) “Comparing Conservation Methods for Waterlogged Wood Using Sucrose, Mannitol and Their Mixture.” In Proceedings of the 5th ICOM Group on Wet Organic Archaeological Materials. Portland, Maine 16-20 August 1993. pp 287-299
Dana Senge’s Notes: Sugar and Mannitol have excellent dimensional stability. Mannitol: smaller molecules, good diffusion characteristics, penetrates quickly, stabilizes wood structure before collapse, food for less degraded woods, lower water solubility than sucrose—therefore it crystallizes before sugar upon evaporation or lower temperature. Sucrose: higher molecular weight than mannitol, a little lower penetration compared to mannitol, forms larger crystals, has higher solubility—is good for mid to high deterioration and bulks the voids in the system. 2 step PEG process minimizes greasy/waxy effect. (Mixture of high and low mw of PEG will not solidify upon drying—resulting in greasy/waxy surfaces) Authors tested theory of two step method with sugar/mannitol—combining to one treatment step. Testing was performed on Japanese woods of various levels of degradation. Results: Sugar and sugar/mannitol treatments effective. ASE a little higher with blend. Mannitol alone—ineffective on low degraded material, whitens material surface when used in concentration higher than 51.2%
++ Morgos, Andras and Setsuo Imazu. (1993) “A Conservation Method for Waterlogged Wood using a Sucrose Mannitol Mixture” In ICOM-CC 10th Triennial, Washington D.C., 22-27 August 1993 Preprints. 1993. Pg 266-272.
Dana Senge’s Notes: Very similar to 1994 article.
Morrison, Lynn (1989) “Treating Waterlogged Moss Rope” ICOM-CC Working Group on Wet Organic Archaeological Materials Feb 1989
Ellen Carrlee’s notes: No details of the PEG treatment given in abstract
* Muncher, D.A. (1991) “The Conservation of WLF-HA-1: the WHYDAH Shipwreck Site.” The International Journal of Archaeology. 1991. 20.4:335-349
Ellen Carrlee’s notes: Wood in 10% PEG 400 unheated, every 2 weeks, concentration increased by 10% until 50% concentration reached after 10 weeks. Easier to change solutions than add biocides. Freeze dried. Afterwards, PEG 3350 applied with brush in molten state, cooled with blow dryer and excess removed with cheesecloth.
* Murray, Howard. (1982) “The Conservation of Artifacts from the Mary Rose.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp. 12-19
Ellen Carrlee’s notes: Wood treated was poplar, oak, ash and softwoods. Passive holding included spraying with boric acid and double wrapping in sealed polyethylene sheeting (dried out somewhat and got cracking and salt efflorescence within 6 months) or submersion in water (resulting in additional expansion and softening.) Pre-treatment with 5% EDTA as well as ultrasonic cleaning to remove salts and iron corrosion products, although more than 48 hours in EDTA resulted in notable softening. PEG 3400 up to 50%. Mostly doing freeze drying, although getting good results with drying only the surface in the freeze drier and then allowing it to air dry. Excess PEG removed with hot air, IR lamps, and ethanol swabs. Reconstruction done with wooden dowels, nitrocellulose adhesive and melted PEG 6000 at 50% as a surface coating.
Park, J. (1997) “The Barton-on-Humber Project: A Large Collection of Waterlogged Wood: Data, Retrieval, Storage, Pre- and Post-Treatment Methods.” In Proceedings of the 6th ICOM Group on Wet Organic Archaeological Materials, York, 1996.
++Powell, George M. (1980) “Polythylene Glycol.” Chapter 18 in Handbook of Water-Soluble Gums and Resins ed. By Robert L. Davidson. New York: McGraw-Hill. pp 18-31.
++ Purdy, Barbara. (1996) How to do Archaeology the Right Way. University of Florida Press. Gainesville, Florida.
Dana Senge’s notes: Chapter 4 Degradation, Preservation and Curation. Favorable conditions in natural environments that prevent degradation of plan and animal material…locations that remain continuously frozen, wet or dry (stability of environment). Her standard PEG treatment: 10% PEG (preferably 540) increased incrementally by 10% each month until you reach 80% (~ 8 months) Noted that PEG used to treat cordage, nets and baskets require different molecular weights. Example of textile from Windover Site: freeze dry and treated with parylene. Sugar another option but attracts insects. Refers to PEG as similar to antifreeze.
Ellen Carrlee’s notes: Purdy is an archaeologist teaching in the field since 1967. She has conservation awareness, attended the 1981 WOAM conference in Ottawa, for example.
* Rice, J.T.(1990) “Glueing of Archaeological Wood,” In R.M. Rowell and R.J. Barbour (editors) Archaeological Wood Properties, Chemistry and Preservation. Advances in Chemistry Series 225, American Chemical Society.
Ellen Carrlee’s notes: includes info about adhering PEG treated wood and suggests solvent systems are better than aqueous ones for that purpose, which is helpful for thinking about consolidation too.
* Rodgers, Bradley. (1992) ECU Conservator’s Cookbook: A Methodological Approach to the Conservation of Water Soaked Artifacts. Chapter 2: “Waterlogged Wood.” Herbert P. Paschal Memorial Fund Publication. East Carolina University.
Ellen Carrlee’s notes: ECU= East Carolina University. Dr Bradley Rodgers teaches conservation of material from underwater environments. Don’t put items from saltwater directly into fresh water, needs to be gradual or the salt water moves out faster than freshwater can move in, causing collapse (ie pruny fingertips in the bath.) Specific gravity of several woods are given. Pits in cell walls have valves, and if these are blocked it is harder to impregnate the wood. Hard to see w/o SEM. PEG solution is heated, and you weigh it weekly after you achieve 50% PEG. Should stabilize at about 20% weight gain. Might go up to 35%. If you’re using PEG 3350, maybe even 45% Wood in good condition sometimes as little as 15%. Sucrose treatment described. Brush coating of 50% PEG 3350 to consolidate the outer layer. Ellen’s note: Bradley’s treatments don’t always match up to AIC standards and ethics, and there was a big dustup over one of his recent publications, an update and expansion of the material in this book. Does this say more about AIC or about Rodgers? What is really going on with AIC and the archaeology world anyway?
*++ Rowell, Roger M. and R. James Barbour (1990) (editors) Archaeological Wood Properties, Chemistry and Preservation. Advances in Chemistry Series 225, American Chemical Society. Washington DC.
Dana Senge’s notes: Valuable text include articles by Florian on history of archaeological wood, treatments, storage, future research.
* Sakuno,Tomoyasu, and Arno P. Schniewind. (1990.) “Adhesive Qualities of Consolidants for Deteriorated Wood.” Journal of the American Institute for Conservation. Vol. 20. No. 1. 1990 pp.33-44.
Ellen Carrlee’s Notes: For dry archaeological wood not treated with PEG, The adhesive strength of Butvar B-98 for glue line impact shear strength was higher than B-72 and AYAT but less than PVA emulsion. Butvar, B-72 and AYAT are all effective consolidants, it seems.
* Saupe, Dr. Stephen G. (2009) “Cell Walls –Structure and Function” Plant Physiology (biology 327) College of St. Benedict/ St. john’s University. Collegeville, Minnesota. 2009. http://employees.csbsju.edu/ssaupe/biol327/Lecture/cell-wall.htm
Ellen Carrlee’s notes: good description of the cell wall using plain language but lots of detail. Hemicellulose is now called “cross-linking glycans.” Good discussion on bonding and formation as well.
* Schaffer, Erika. (1976) “The Preservation and Restoration of Canadian Ethnographic Basketry.” Studies in Conservation. Vol 21 no. 3. 1976
Ellen Carrlee’s notes: 25g PEG 600, 20g glycerine dissolved in a 75% aqueous ethyl alcohol solution to yield 100g. Applied with a brush on both sides of the basket (birch bark) daily. Treatment done in 1970, but the entire article ONLY deals with deformed DRY material…this article is not about waterlogged material at all, or even damp stuff.
++ Schindelholz, Eric et all. (2007) “An Evaluation of Supercritical Drying and PEG/Freeze drying of Waterlogged Archaeological Wood.” A report for NCPTT grant. 2007
Dana Senge’s notes: Compared PEG/Freeze drying, Air drying, Supercritical Drying. Overall PEG/Freeze drying gave best treatment results, least amount of shrinkage. (similar results to Barry Kaye). PEG=cryoprotectant. Supercritical drying technique: replace water with methanol (methanol exchange process) for a period of 4 weeks (length of solvent exchange treatment determined time through methanol endpoint determination)*, pins set in samples and measured to track shrinkages, then run in batches through supercritical drying system. *test samples were placed in methanol baths. New baths every 7 days. Old baths were analyzed using Karl-Fischer titration to determine water concentration. Water content was less than 5% after 2 weeks and 1% after weeks 3 and 4.
*Schniewind, Arno P. and Peter Y. Eastman. (1994) “Consolidant Distribution in Deteriorated Wood Treated with Soluble Resins.” Journal of the American Institute for Conservation. Vol. 33, No. 3, 1994. pp 217-255.
Ellen Carrlee’s notes: SEM investigation into dry deteriorated archaeological wood not treated with PEG, but consolidated with B-72, Butvar B-90 and Butvar B-98. Resin was not uniformly distributed. Reverse migration is blamed.
*Schniewind, Arno P. and Carlson, S.M., (1990) “Residual Solvents in Wood Consolidant Composites.” Studies in Conservation. Vol. 35, No 1. Feb 1990.
*++Schniewind, Arno P. (1990) “Consolidation of Dry Archaeological Wood by Impregnation with Thermoplastic Resins.” In Rowell, R.M. and R.J. Barbour (1990) (editors) Archaeological Wood Properties, Chemistry and Preservation. Advances in Chemistry Series 225, American Chemical Society. Washington DC
Ellen Carrlee’s notes: Suggests Butvar B-98, Acryloid B-72 and AYAT as the most likely resins to be successful in consolidating dry archaeological wood (not treated with PEG)
*Seborg, Ray M. and Robert B. Inverarity. (1962) “Conservation of 200-Year-Old Water-logged Boats with Polyethylene Glycol.” Studies in Conservation. Vol 7 No 4 1962 pp. 111-120
Ellen Carrlee’s notes: Similar to Science article. Wooden boats 200-300 years old in Lake George excavated, made of white and yellow pine as well as white oak. Oak was OK, but pine badly degraded. 50% PEG 1000 was used at room temp from 4 hours to three weeks, and by multiple dip treatment. Wood was air dried at 80F and 30% RH. When treated for 7 days, the white pine had 60% retention of PEG, yellow pine had 35% and white oak 13%. Treating the white pine for 2 days was as effective as treating it for 7 or 21 days. Wood treated this way gets damp above 80% RH and sweats at 90%. Reduced solubility of PEG with a higher molecular weight can be easily overcome by a moderate increase in temperature.
*++ Seborg, Ray and Robert Bruce Inverarity. (1962) “Preservation of Old, Waterlogged Wood.” From Science: 18 May 1962, vol 136 no. 3516. pg 649-650.
Dana Senge’s Notes: Sited by Grosso and others as starting recipe for treatments at Ozette, Conway, Wapato. Process used to dry 200 year old waterlogged boats from Lake George, NY. Recognizes that treatment of waterlogged wood has been a problem for archaeologists and museum conservators for a long time. Experiments done by Adirondack museum in Blue Mountain Lake NY and US Forest Products Lab in Wisconsin. Treatment: 50% PEG 1000 in 50% aqueous soln, room temp for 4 hours to 1 week and multiple dip treatments, Dried @ 80 degrees F and 30% RH. Shrinkage observed: untreated = 5-7% Treated for 2-7 days=0.5%. Shorter treatments 4-24 hours=2-4%. Observed improvement in reduction of surface checking regardless of treatment length. Materials were 1/2-1” thick planking (white oak, white and yellow pine) Noted—Wood treated with PEG 1000 becomes damp under high moisture conditions: above 80% RH (will sweat or bleed at 90% RH) Recommends higher molecular weight because it is less hygroscopic (may require heat to facilitate impregnation).
* Singley, Katherine. (1988) The Conservation of Archaeological Artifacts from Freshwater Environments Lake Michigan Maritime Museum, South Haven, Michigan 1988.
Ellen Carrlee’s notes: She tends to use PEG 300 and 400 with 4500 applied later hot. Recommends pretreating wood contaminated with iron salts with 3% perchloric acid, soaked for about a week. This dissolves iron and opens up the pore structure to increase the penetration of PEG. PEG 300 at room temp 10% for six months, then removed and wrapped in plastic with regular surface brushing of higher concentrations 3X a week increasing the concentration every two months until 80% reached. Slow drying at high RH was used. 50% PEG 4500 paste was then applied with hot air. This layer was thought to prevent oozing out of lower MW PEG. She also uses 10% PEG 300, soaked for a year and then freeze dried.
* Smith, C. Wayne. (2005) “Rethinking Conservation Paradigms for the Preservation of Waterlogged Wood.” WAG Postprints, Minneapolis Minnesota. 2005.
Ellen Carrlee’s Notes: PEG decomposition creates aldehydes, ferrous, ferric, and cupric salts. Trouble with PEG when it interacts with compounds and oxides found in waterlogged wood. PEG treatments cause some cellular collapse or cell wall distortion. Long term reactivity of PEG is an issue. Smith likes polymerization as a technique.
* Smith, C. Wayne (1997) Retreatment of PEG Treated Waterlogged Wood Conservation Research Laboratory Texas A&M. 1997
Ellen Carrlee’s notes: Claims that PEG becomes unstable over time and there’s movement within the wood. Suggests method for retreatment extracting PEG and crosslinking remaining PEG. Ellen’s note: there are more references where Smith discusses the shortcomings of PEG.
++Smith, Derek. (1964) Archaeological Excavations at the Beach Grove Site, DgRs1, During the Summer of 1962. BA Thesis. UBC
Dana Senge’s notes: Site was shell midden, NE corner of Point Roberts Peninsula in Delta Municipality, BC. Fiber materials were found in stratum of finely textured blue clay at eastern fringe of midden—adzing detritus and twisted rood strands including basketry. Pg. 50 describes Basketry/Matting found in clay layer. Radiocarbon date of charcoal at site: 363 +/- 120
* Spirydowicz, K.E., E. Simpson, R.A. Blanchette, A.P.Schniewind, M.K.Toutloff, A. Murray, (2001), “Alvar and Butvar: The Use of Polyvinyl Acetal Resins for the Treatment of the Wooden Artifacts from Gordion, Turkey”, Journal of the American Institute for Conservation, Vol. 40, No. 1, 2001, pp 43-57.
Ellen Carrlee’s notes: the wood was not PEG treated. This is one of the important studies regarding Butvar B-98 on archaeological wood. It was used 10% in 60:40 ethanol and toluene.
* Stamm, A.J. (1959) “Effect of Polyethylene Glycol on the Dimensional Stability of Wood.” Forest Products Journal, Vol. 9 No 10 October 1959. pp373-378.
Ellen Carrlee’s Notes: Typical of early literature on PEG, many more articles like this one at the ASM conservation lab. Stamm was looking into PEG as early as 1956. Green wood soaked overnight in 30% PEG 1000 is recommended. Gluing tests are described.
* Stark, Barbara L. (1976) “Waterlogged Wood Preservation with Polyethylene Glycol.” Studies in Conservation Vol. 21. 1976 pp.154-158.
Ellen Carrlee’s notes: 1969 excavation Alvarado, Veracruz, Mexico found wooden bowls with polychrome painting, around AD. 300, Gliricidia sp., in brackish water. PEG 1540 was chosen because PEG 1000 would be hygroscopic in conditions about 80% RH. Did not use PEG 4000 because she feared it would loosen the paint and she did not want to use heat. Tried 13 days soaking in saturated solution of PEG 1540 at 28C, thought to be over 70%. Larger pieces soaked 60-75 days. Added more PEG as time went on a wood absorbed it. Slowly air dried in a humid environment. Shrinkage up to around15% and minor warpage. Glued together with Duco before fully dry
Dana Senge’s notes: Waterlogged wooden bowl with polychromy– Alvarado, Veracruz, Mexico. No Field Treatment- shipped to New Haven for treatment—shipment delays from field to lab caused some drying. Treatment: Carbowax 1540 selected—1000 is hygroscopic @ humidity conditions about 80%– not as much of an issue with 1540—but still damp when handled?
Storch, Paul. (1997) “Non-Vacuum Freeze-Dry Treatment of Two Leather Objects.” in Leather Conservation News. Vol 13 no 2. 1997. pg 15-17.
Dana Senge’s notes: Described Peg Treatment of two leather boots followed by freezing then freeze drying in non vacuum freeze drier. Freeze drying: objects placed in polypropylene container with silica gel.
Ellen Carrlee’s Notes: Might be helpful for us in drying PEG treated basketry without a freeze dryer using a low-temp freezer.
* Straetkvern, Kristiane. (2002) “Freezing of Polyethylene Glycol: Compressions Strengths and freezing Curves for High-Molecular Weight PEGs with and without Low-Molecular Weight PEGs Added.” In Proceedings from the 8th ICOM Group on Wet OrganicArchaeological Materials Conference. Stockholm, 11-15 June 2001. pp.335-352.
Ellen Carrlee’s notes: Straetkvern suggests compression strength of wood is greater for high molecular weight PEG treatments done without low molecular weight PEG.
* Titus, Larry. (1982) “Conservation of Wooden Artifacts.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp153-158.
Ellen Carrlee’s Notes: Excavation in 1978, help from the Museum of Archaeology and Ethnology at Simon Fraser University and Dept of Archaeology indicated that previous waterlogged basketry and cordage did not have successful treatment, with PEG flaking off or crystallizing on surface of fragile artifacts. So they soaked the hardened fatyy midden matrix from the surface with acetone and painted with Neatsfoot oil, then immersed in Ethulose if needed. Seemed to have worked OK with the wood, most of which was fairly sound. Conservator Charles Hett commented that the good preservation was due to the fat content. Several hundred wooden pieces excavated from Barrow in 1981 (Utkiavik Archaeology Project) about 150 treated in the field. Air dried, brushed to remove dirt, then soaked in water and then PEG 4000 (although some PEG 1000 was used at first.) Immersion between 48-165 hours. Then it was air dried and sprayed with Lysol (ortho phenylphenol.) Wow, I wonder where these pieces ended up?
++ Turner, Nancy J. (1998). Plant Technology of First Peoples in British Columbia. UBC Press: Vancouver.
*Unger, Achim; Arno P. Schneiwind, Wibke Unger. (2001) Conservation of Wood Artifacts: A Handbook. Natural Science in Archaeology Series. Springer Verlag. New York.
Ellen Carrlee’s notes: Contains excellent chronological lists of when major treatments and innovations occurred and who did them.
*Viduka, Andrew. (2002) Survey of Methods Used by Some Large institutions Specializing in the Conservation of Wet Organic Archaeological Materials. Report as the 2002 Churchill Fellow: Winston Churchill Memorial Trust of Australia.
Ellen Carrlee’s Notes: Viduka visited several labs and wrote up his observations. Texas CRL sees, among other things, darkening of surfaces with high PEG concentrations as a disadvantage. Parks Canada was looking at whether PEG modifies the crystal size of water. Tara Grant at CCI has generally found air-drying to be unsuccessful. Wooden material from Nydam Mose, 5th C Iron Age site treated in Denmark, is highly deteriorated with only lignin remaining. NMD is looking into sucrose, wood flexibility post-treatment, Cellusolve method, lots of vacuum freeze drying, review of old treatments, deacidification of low mw PEG timbers, experimental cold air drying. On the Vasa, acid affected areas have white or yellow build-up and generally appear on areas treated with PEG 400 and not PEG 4000. Remedial treatment is a spray with sodium bicarbonate and soda with a pH >10 and covered with plastic wrap. Skuldelev ships were some of the earliest to be conserved with PEG 4000, and 40 years later, they still have a mw of 3900. Using too high a mw on only slightly degraded wood is a problem. Too much PEG would give a purple or blue sheen on the surface. Longer immersion made bigger timbers darker than smaller pieces. Heating for re-shaping caused darkening of the surface. Glenn McConnachie’s PhD reveals that even well-preserved waterlogged oak from the Mary Rose has 30% volumetric shrinkage after air drying.
Vynckier, Jozef. (1965) “Examination and Conservation of Basketwork from a Roman Well at Destelbergen” Bulletin de’Institut Royal du Patrimoine Artistique Vol 8. 1965 (Flemish?)
Ellen Carrlee’s notes: Linden bark basketry fragments immersed 4 months in carbowax 4000
*++ Watson, Jacqui. (2004) “The Freeze-Drying of Wet and Waterlogged Materials from Archaeological Excavations.” In Physics Education. 39(2) 2004 pg 171-176.
Dana Senge’s notes: Anaerobic conditions may have eliminated decay due to microorganisms but material – wood—will slowly dissolve leaving a ligneous skeleton. Freeze drying- requires low T (-28-32° C). dry air flow to remove saturated air from surface of piece. If air around objects becomes saturated sublimation will cease.
* Watson, Jacqui. (1982) “The Application of Freeze-Drying on British Hardwoods from Archaeological Excavations.” . Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981.
Ellen Carrlee’s notes: Fungal degradation in the cell wall contributes to splintering when freeze-dried. Mineral deposition or replacement in outer layers is common in archaeological wood, especially with iron. Sometimes these can be seen as casts of material that is now lost. Chelating agents etc remove the iron. But iron also interacts badly with PEG. Early warning in this article of problems with iron salts and PEG. Even if the soil has low iron content, there is sometimes high iron content in the wood. Oak freeze dried after 10% PEG 400 for 4-6 weeks had deep cracks next to the rays, and some distortion and collapse in some small fibers. Using 10% PEG 400 and 15% PEG 4000 resulted in less cross checking on the surface. Wood that underwent freeze-drying without impregnation collapsed, and showed crystals (calcium and sulphur) that precipitated out that did not do so when PEG was used. Pitting details in the vessels that are useful for ID were obscured after treatment with PEG 4000. Mixed PEG solutions work best when using freeze-drying.
*++ Wevers, Anton J.M. (1991) “Treatment of Waterlogged Rope” Proceedings of the 4th ICOM Group on Wet Organic Archaeological Materials Bremerhaven 1990.
Ellen Carrlee’s notes: Under PEG 1000 does not strengthen and over PEG 1000 makes it too stiff. Cleaned, dried, then impregnated with polyurethane
Dana Senge’s notes: Rope—highly processed cellulose fibers. PEG treatments of MW lower than 1000 do not strengthen; above 1000 no more flexibility. Other impreg options: Cellulose derivatives: hydroxy propyl cellulose and PEG 400, Freeze dry, Polyurethane (E2250—not reversible,) Polymers, Luvis-kol and PEG 4000 Author focused on polyurethane treatment—felt that reversibility wasn’t necessary. Noted- circulation of impregnation bath is important to ensure maintaining equal concentration of liquid in bath and in specimen.
* Wyatt, Mary Pat. (1978) Museum Alaska Newsletter. Vol. 11 No 1. 1978.
Ellen Carrlee’s Notes: Carbowax 540 Blend or Carbowax 4000 from Union Carbide as well as PEG 1500 or 4000 from Dow Chemical. Apparently, PEG could sometimes be found in Anchorage lumber stores. Mixed to a 50% solution and soaked for a month or two, then removed from the 50% solution and soaked in an 80% solution for several months. Rinsing with hot water followed by slow drying in high humidITy was recommended. Thymol and Roccal were the recommended fungicides. Seems to be an article Mary Pat wrote up for Alaskan museums using Grosso 1976 and Stark 1976 as references. The Alaska State Museum also was offering limited supplies of PEG and thymol.
* Young, Gregory S. (1990) “Microscopy and Archaeological Waterlogged Wood Conservation.” CCI Newsletter, No. 6, September 1990. pp 9-11.
Ellen Carrlee’s notes: General overview of PEG treatment/ research. Deterioration greatly improves the ability of PEG to penetrate and treat wood successfully, but most excavated waterlogged wood is only moderately deteriorated. White oak, various cedars, and white ash are hard to penetrate, while aspen, cottonwood, alder and spruce allow greater penetration. Caution with determining degree of deterioration from thin 3mm cross sectioned wafers of wood examined under the microscope, as the sample has a lot of disrupted wood cells and suggests more cell wall accessibility than there really is.
Young, Gregory S. and Richie Sims. (1989) “Microscopical Determination of PEG in Treated Wood – the Effect of Distribution on Dimensional Stabilization.” Conservation of Wood and metal: Proceedings of the ICOM Conservation Working Group on Wet Organic Archaeological Material and Metals. Freemantle, Western Australia Museum. 1987 pp109-140
Ellen Carrlee’s Notes: Fluorescence microscopy. 25-35% PEG 200 and 3350. Found less penetration with larger molecular weights. Dimensional stabilization correlates with full impregnation of secondary cell wall. Eight different species tested showed broad range of access to cell wall.
*Young, Gregory S. (1982) “Polyethylene Glycol Localization within the Structure of Waterlogged Wood.” 9th International Congress on Science and Technology in the Service of Conservation. 1982.
Ellen Carrlee’s Notes: Cobalt thiocyanate staining shows that stabilization depends on how much water is replaced by PEG in cell walls, and also the molecular size of the PEG. In Aspen wood (Populus sp) PEG 400 penetrates the capillary network in cell wall, but at 35% much better than 15%. PEG 3350 does not penetrate the capillary network as well.
*Young, Gregory S. and Ian N.M. Wainwright. (1982) “Polyethylene Glycol Treatments for Waterlogged Wood at the Cell Level.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp.107-116
Ellen Carrlee’s notes: Shrinkage happens when hygroscopically bound water within the cell walls is lost when wood is below the fiber saturation point (FSP.) Lower MW PEG is expected to stay in the cell wall, while higher MW PEG bulks the lumina. Cobalt thiocyanate is a microscopical stain when dissolved in non-aqueous histological grade cedarwood oil. The oil (cedrene and cedrol) is immiscible with both water and PEG. It dissolves the cobalt thiocyanate, but readily gives it up to the PEG in wood sections.
PEG 400 (35%) in cell wall capillary matrix
PEG 3350 (60%) bulked cell lumina
PEG 540 blend (64%) in both cell wall and lumina 540=1450 + 300 together equal MW mixture
Over 3000 shouldn’t get into cell wall, above 2000, should be impeded somewhat. MW below 400 penetrate better. PEG must penetrate the cell wall for best dimensional stability. Double bulking is good, though.
++____ (1976) Field Conservation at Ozette Discussion Session. September 22, 1976
Dana Senge’s Notes: pg 93: Grosso discusses the needs of the Ozette site: helicopter access a couple times a month, not necessarily regularly spaced. Means that artifacts cannot be regularly removed from the site. Set up tanks in the field, can treat many of the materials onsite in one month time period. Then transfer to Neah Bay after treatment. Best use of time and specific circumstance. Pg 94. discussion of polymerized oils on bone combs etc. Thought to be seal oil (similar to linseed) was broken down with 1:1:1 dichloromethane:methanol: petroleum ether. Film documentation of site- Ruth and Louis Kirk as well as KOMO Pg 96: questions about soil studies- observation by Mibach that reddish slime exists at site: iron present in cellular structure of artifacts? Sulphate reducing bacteria? Grosso response—sulphate reducing bacteria has been found on occasion- used Cytox to counteract. Early on used Borax/Boric acid to reduce bacteria and keep solution sterile, but some workers fount it irritating—skin and respiratory
*________(1982) “General Discussion Period Session II Analysis and Classification of Wood.” Proceedings of the ICOM Waterlogged Wood Working Group Conference Ottawa 1981. pp.117-121
Ellen Carrlee’s notes: Howard Murray: Exposure of object to higher grade solution leached out the previous PEG of a lower solution.
* _________________ “Treatment for Dugout” Unpublished, pre-1980? Given to former Alaska State Museum conservator Betty Hulbert by the Anthropology Conservation Lab at the Smithsonian.
Ellen Carrlee’s notes: Build a tank deep enough to allow a foot of liquid to cover the boat, line the tank with polyethylene sheeting. 25% PEG 1000 and 5% solution of Roccal fungicide. Leave in solution for at least 3-4 months, then evaporate off by lifting the plastic cover until the top of the liquid reaches the boat (This will apparently increase the concentration of PEG?) Then drain tank and air dry very slowly. Surface may be treated with polyurethane varnish. There is no evidence that this treatment was ever used at the Alaska State Museum, perhaps Betty Hulbert simply had a copy.