Cost of Museum Supplies

September 19, 2013
supplies board

Sample board of supplies and comparative cost per square foot. In the collections processing room, Alaska State Museum, summer 2013

As the Alaska State Museum gears up to move out of its old facility, we’ve been busy ordering and consuming supplies to ready collections for the move.  When you have a choice about what material to use in a given application, which one is more economical?  For the new staff, volunteers, and contractors…what materials are we talking about?  I put together a sample board of products and how much they cost per square foot, mounting the items with hot glue on a sheet of Coroplast and hanging it on the wall above one of the workstations where people are making storage supports.  I’ve also got a list of what we’ve been using in summer 2013, where it comes from and how much it costs per square foot.  Remember, we’re in Juneau, Alaska.  Yes, we are the capital city but we are not on the road system.  Everything comes here by boat or by airplane.  Shipping costs are a big deal.

ITEM SOURCE $$ SQ FT w/shipping
Backer Rod 3/8” GoodHardware $0.21
Backer Rod ½” GoodHardware $0.24
Backer Rod 5/8” GoodHardware $0.27
Blotter paper Talas $1.01
Blueboard Bflute Talas $0.92
Blue tape 1.14” Home Depot $0.04
Corex Local, AJE $0.94
Coroplast Metal Edge $1.88
Polyethylene Foam 1” IR Specialty $4.35
Polyethylene Foam 2” IR Specialty $5.92
Polyethylene Foam 6” IR Specialty $12.04
Foam Cor Metal Edge $1.21
Marvel Seal Talas $1.04
Matboard Daniel Smith $2.05
Minicell 1” IR Specialty $3.40
Muslin thin JoAnne $0.22
Muslin thick JoAnne $0.60
Mylar 3mil Talas $0.29
Pallet Wrap 3” AIH ½ cent
Pallet Wrap 15” AIH $0.02
Reemay Talas $0.90
Stockingette 6” Fisher Sci $0.33
Teflon tape 1” AIH $0.05
Teflon tape ¾” AIH $0.04
Teflon tape ½” Home Depot $0.06
Tissue Talas $0.09
Trapez. Rod 1” Univ. Products $1.50
Trapez. Rod 2” Univ. Products $2.41
Twill Tape 1” Talas $0.21
Tyvek Homewrap Home Depot $0.13
Tyvek tape 2.25” Talas $0.31
Tyvek Softwrap MasterPak $0.27
Volara 1/8” Fisher Sci $0.85
Volara  ¼” Fisher Sci $3.05

How to calculate square feet: multiply L x W in inches, then divide by 144 (12 x 12 is a square foot).  Then visualize and imagine if that makes logical sense.  Our collections room floor tiles are one square foot.  I have a bigger spreadsheet that breaks out columns for how much product and what the shipping costs are, but just posted the conclusions in the table above.

In June 2013, I checked AIH, Home Depot, Valley Lumber and JoAnne in search of products I might get locally especially Teflon tape, tyvek, twill tape, blue tape, pallet wrap, backer rod, and muslin.  Valley Lumber has palletizer, too, supplied by U-line with a cardboard tube.  The 20” is cheaper than the AIH 15”, but their 3” costs more. Home Depot palletizer is green colored, which makes us museum folks suspicious of unnecessary additives or the risk of staining.  Please note, we don’t use blue tape or pallet wrap for storing our collection, just for moving it.  More postings on that to come…

Home Depot Tyvek is Homewrap, not needle punch softwrap, and has words printed on it. Valley Lumber carries Tyvek Homewrap, too, but it costs more.  Beware: “Tyvek tape” we want is made of white Tyvek carrier, not the kind of clear carrier tape that is used to tape Tyvek to Tyvek.  If you’re curious about what all these products are made from and what museums use them for, check out the excellent website CAMEO (Conservation & Art Materials Encyclopedia Online), a searchable inormation resource developed by the Museum of Fine Arts, Boston.

Tri Rod is no longer on the market, replaced by trapezoidal rod from University Products.  However, it looks from images on the web that it might not have the smoothness on all exterior surfaces that we like.  We ordered some and will evaluate.

Sources:

Local sources include Alaska Industrial Hardware (AIH), Home Depot, Valley Lumber, Good Hardware, and JoAnne Fabrics.

The State of Alaska has a contract with Fisher Scientific, which includes a discount and free shipping.  This is a huge savings for us.

Our local source for affordable Corex is a sign printing company for where our exhibit designer AJE used to work.  Technically, we should call this stuff Corflute sheet, as Corex is the manufacturer who makes this twin walled polypropylene sheet.  but the local sign company we buy from calls it Corex, so we’ve fallen into the habit too.   While I’m at it, I might as well mention my flagrant abuse of the term “Ethafoam” here too…we tend to use it for any good quality polyethylene foam we use, much in the same way folks might say “Kleenex” for a different brand of facial tissue.

Talas, Metal Edge, Daniel Smith, MasterPak and University Products are vendors with an online presence that are often used by museums.  We have found them the most cooperative of the many vendors available when it comes to Alaskan shipping issues.

IR Specialty is a specialty foam company in Fife, Washington that also has a website.


CM Times Vintage Newsletters

March 30, 2012

Conservation Materials Limited was a conservation supply company run by Doug and Dorothy Adams.  This business was important to the development of the conservation profession, and put out several newsletters which are of interest to us today.  I believe every treatment report should have a “rationale” section in it, to explain choices conservators are making.  Sometimes it is necessary to sleuth out those past choices today, for either research or current treatments.  Here are pdf scans of the old CM Times newsletters, which contain both useful information and are still an interesting read today.  I was looking into this company to date some supplies in my lab (see posting called Dating Conservation Supplies) and thought this would be worth sharing too.  Below the pdf scans is a best-guess timeline of the company.   Corrections or additions most welcome.

CM Times 1

CM Times 2

CM Times 3

CM Times 4

CM Times 6

ConsMatLtd June 1991

CONSERVATION MATERIALS LTD

1978 (spring): Dorothy and Douglas Adams bought Conservation Materials Ltd and moved to Sparks, Nevada where a shipping distribution center was available.  (source: WAAC newsletter profile on the owners 1986)

1980’s: Located at 240 Freeport Blvd Box 2884  in Sparks, NV.  TELEX 377405 Phone  (702) 331-0582 (from what I understand, telex is like a telegraph-based predecessor of the fax machine)

1989 – Early 1990’s: Moved to 1165 Marietta Way  PO Box 2884.  Still in Sparks, NV.   (702) 331-0582 FAX (702) 331-0588

New labels include NEW FAX number which was mentioned in WAAC newsletter in 1989

1993-95?: Located at 1275 Kleppe Lane #10 PO Box 2884 Sparks, NV.  New address mentioned in Sept 1993 WAAC newsletter

1994, May 20: Douglas Adams died in a car accident, Dorothy continued the business.   Many conservators wrote their remembrances of Doug in the WAAC Newsletter Vol 16 No 3 September 1994 page 5.

http://cool.conservation-us.org/waac/wn/wn16/wn16-3/wn16-303.html

1996: By now, the business is at 1395 Greg Street Suite #110, Sparks, NV  Phone: (702) 331-0582 FAX (702) 331-0588

1997: Out of business.  Dorothy Adams apparently started a similar business, but sold it in July 1997.

CONSERVATOR’S EMPORIUM

1997:  It seems there was some sort of rough transition between Conservation Materials Ltd and Conservator’s Emporium.  The latter was run by William and Yolanda Foster.  He was a business consultant and she was a chemist.  New address 100 Standing Rock Circle in Reno, NV (Abby Newsletter V 21 #3 Sept 1997)

1999:  Conservation Materials Limited used to make Quake Wax, but rights to the product were acquired in 1999 by Trevco, Makers of Quakehold!  Museum Wax, Clear Museum Gel and Museum Putty.

2004:  Flurry of distlist email rumors about Conservators Emporium being out of business or lagging far behind in their orders.  Owner William Foster writes in July of 2004 to say he has $30,000 in unpaid receivables and the business is struggling.  Sold to MuseuM Services Corporation in 2005.

MUSEUM SERVICES CORPORATION

1968: founded

2005: Peter Mecklenburg of MuseuM Services Corporation announces that it acquired Conservator’s Emporium as of November 1, 2005.  New location is 385 Bridgeport Drive, South St Paul, Minnesota.

2012: Quick check of Museum Services Corporation website on 3/30/2012 still gives their contact info as follows: MUSEUM SERVICES CORPORATION 385 Bridgepoint Way, South Saint Paul, Minnesota 55075 USA Phone: (651)450-8954 Fax: (651)554-9217 E-Mail: info@MuseuMServicesCorporation.com


Collections Labeling: Simple Kit

November 25, 2011

Collections label kit for small museums

This is the kit I made for a workshop at the Museums Alaska conference in Valdez, September 2011.  The kit is designed for small museums with wide-ranging collections with everything from natural history specimens to fine art, where limited staff must wear many hats.  I made 24 kits, since many things can be ordered in a case of 12, and each kit cost about $50.  The workshop was funded through a grant from the Alaska State Council on the Arts.  The kit includes a manual, which can be found at the posting Collections Labeling: Material by Material. Other adhesive choices can be found on the posting Collections Labeling: Alternate Adhesive Testing.

 CONTENTS:

Acetone in dropper bottle (I got the bottle and acetone from Fisher Scientific)

  • Used for removing B-72.
  • Reagent Grade.
  • Hardware store acetone has petroleum distillates, other impurities.  Will work, but may make paper translucent and hard-to-read on dark materials. Could behave unpredictably with B-72.
  • Acetone is main ingredient in nail polish remover.  Fumes may be irritating.
  • Flammable.

Cotton swabs (Local grocery store)

  • Simple Q-tips.
  • Think twice about rubbing solvent on the surface of your artifact.

Funnel, mini (I bought these on the internet from Amazon.com)

  • For transfer of adhesive into smaller brush bottle, like polish bottle.
  • When B-72 dries on tools or jars, it can be soaked in water overnight, and then peeled off.

Needles, assorted (Local fabric store)

  • Sharps are good for piercing Tyvek label, but could stab through fibers.
  • Blunts or ball points are good for getting in between the weave gently.
  • Cheaper needles often have poorer quality “eyes”.

Paraloid B-72 adhesive  (I ordered pre-mixed for labeling from Talas)

  • Use to apply the paper label.
  • Synthetic acrylic resin: 70% ethyl methacrylate 30% methyl acrylate copolymer.
  • Works best no thicker than maple syrup most of the time.  Even thinner is often fine.
  • If you want to mix B-72 yourself, Howard Wellman describes how on the SHA website.
  • Soluble in acetone, but does not go into ethanol easily.  Ethanol sometimes added to slow drying time.
  • If it bubbles, try adding more acetone to your jar of adhesive.
  • If the top coat smears the writing, try loading brush well and applying in single thick stroke.
  • If it still smears, could try artist acrylic gloss medium as a top coat, applied smaller than barrier coat.
  • B-67 is similar to B-72 but in mineral spirits instead of acetone. This is sometimes used a top coat.
  • Aquazol is sometimes used to coat or size the label paper first, making the ink less likely to smear.
  • B-72 is thermoplastic, so if the lid sticks, running under hot water or using a hairdryer can help get it unstuck.

Pen, Zig Millenium  (I ordered online from MarkerSupply.com)

  • Use this pen for writing on tags and Tyvek.
  • “Permanent” boasted by many pens often just means waterproof, not lightfast or non-bleeding.
  • Dye-based inks often smear.
  • Carbon black ink is lightfast: India ink or rapidograph ink.
  • Quill pens take practice, can be gloppy, sharp, and may scratch.
  • Technical pens are fussy (clog, need cleaning fluid, delicate tip, may scratch).
  • IdentiPen also recommended for writing on plastic bags.
  • Helen Alten has a good article about testing pens for artifact labeling.

#2 Pencil  (Local office supply store)

  • HB pencils are also OK.
  • Wonderfully reversible on many surfaces, especially paper, if you don’t press too hard.

Photo Pencil  (I ordered from Hollinger Metal Edge)

  • Use these for marking the back of photos printed on plastic.
  • If you have a plastic photo, the right balance of sharp/dull regular #2 pencil may work if the plastic isn’t greasy from fingerprints or plasticizers.

Polish bottle with brush lid for B-72  (I ordered online from Amazon.com)

  • Nail polish is no good…yellows, cracks, peels, ages poorly, crosslinks.  Remember, how long is it meant to last on your fingernails?
  • Correction fluid or Wite Out is also not OK, it peels off too easily, ages poorly, proprietary mix varies widely.
  • Nice to buy B-72 already made, but the wide lid container causes it to dry out too fast.
  • Use mini-funnel to transfer from bigger container into polish bottle.  Also, if one jar dries out you have a back-up.
  • When applying, think of a sandwich made by two layers of B-72 with label in the middle.

Small scissors  (I got these from Fisher Scientific, but McMaster Carr also has them at a good price.)

  • Cut your labels into fringe for ease of handling multiple small numbers.
  • Rounding the corners makes labels less likely to snag and pop off.
  • Sewing scissors work well for this use, too.

Small paper tags  (I ordered these from Amazon.com)

  • Don’t use colored string.  Sometimes it runs or bleeds.  Replace with white string.
  • Avoid tags with wire, wire edges, or metal grommets around holes…risks of scratching and rust stains.
  • If your budget permits, you might want to upgrade to artifact tags from archival supply companies.  However, these are about 13 cents each as opposed to 1 cent each for the Avery brand office-supply variety, which test slightly more alkaline (pH 7-8) than the expensive ones (pH 6-7).  Both come with white cotton string.

Thin labeling paper  (I ordered from Hollinger Metal Edge, sold as “Photo-tex”)

  • Interleaving tissue is nice.
  • As thin as will go through your printer or photocopier.  Might need to experiment with feed.
  • Write the method that will work on your equipment on the cover of the folder you keep paper in.
  • Some Japanese tissues may be too thin to print, or may get translucent with adhesive.
  • Snipping your list of numbers into fringe helps keep track of tiny labels.
  • Manipulation by curling over the fingernail to conform to curves or folding lengthwise for long items.

Thread, white cotton  (Local fabric store)

  • Rule of thumb, tie material should be softer than the object, so abrasion will damage the tie and not the artifact.
  • Cotton is non-abrasive.  Polyester is a little bit abrasive.
  • Don’t use with beads that have glass disease, it may help wick moisture inside.
  • “Glide” or other brands of Teflon dental floss OK. Plumber’s Teflon tape is OK.
  • Regular dental floss not so good.  Usually made of nylon and ages poorly, becoming brittle and breaking.
  • Plastic zip ties usually too rough, and are also usually nylon and degrade, get brittle, break.
  • PVC plastic degrades and releases acids.

Tweezers  (I ordered them from McMaster Carr)

  • Pointy ones are helpful for manipulating paper labels.

Tyvek, for labeling textiles  (Local office supply store)

  • Tyvek is spun-bonded from olefin fibers, an inert plastic.
  • Mailing envelopes and home wrap are usually Tyvek and it is OK to use the non-printed, bare areas.
  • Needle punch “soft” Tyvek and smooth “hard” Tyvek both OK.
  • Alternatives: twill tape, Reemay.  Twill tape sometimes hard to write on without ink bleeding.

White vinyl eraser   (Local art supply store)

  • For removing pencil marks.
  • Can be helpful for removing tape residues from price tags or stickers as well.

REFERENCES

Alten, Helen “Numbering Museum Collections: Labeling Ethnographic Objects.”  ICOM Ethnographic Conservation Newsletter Number 17, April 1988 pp.18-21.

http://www.collectioncare.org/cci/ccin.html

Braun, Thomas J. “An Alternative Technique for Applying Accession Numbers to Museum Artifacts.” Journal of the American Institute for Conservation Vol 46. Summer 2007. Pp 91-104.

http://www.mnhs.org/preserve/conservation/docs_pdfs/ApplyAccessionnos.pdf

Buck, Rebecca A. and Jean Allman Gilmore.  MRM5 Museum Registration Methods 5th Edition.  AAM Press. American Association of Museums. Washington DC.  2010

 Davidson, Amy, Samantha Alderson and Marilyn Fox. “Assembling an Archival Marking Kit for Paleontological Specimens.” 2006 (and more too!)

http://collections.paleo.amnh.org/34/labeling

 Wellman, Howard “Mixing Resin Solutions.” Society for Historical Archaeology website 2006.

http://www.sha.org/research_resources/conservation_faqs/documents/MixResin.pdf


Collections Labeling: Material by Material

November 25, 2011

This is the manual included in a kit I made for a workshop at the Museums Alaska conference in Valdez, September 2011.  The 2011 workshop was funded through a grant from the Alaska State Council on the Arts.  The kit is designed for small museums with wide-ranging collections with everything from natural history specimens to fine art, where limited staff must wear many hats.  My preferences come from (1) labeling thousands of artifacts while I was a curator at the Juneau-Douglas City Museum and (2) providing outreach assistance to museum staff statewide in Alaska who need easy simple solutions to collections management issues.  In general, I follow the paper label technique described by Thomas Braun in JAIC Summer 2007. The text below is from the little manual I enclosed in each kit.  If you want the little manual, just print out this manual for collections labeling , cut it in quarters and staple it together.  The contents of the kit are listed and explained in the posting Collections Labeling: Simple Kit.   Some adhesive choices are described in the posting Collections Labeling: Alternate Adhesive Testing.

Here's a labeling challenge: a box of muskox fur!

The back cover of the manual includes these questions to help determine the best labeling technique:

1. Will applying this label cause damage such as new holes or dissolving the surface?

2. Will future removal of this label cause damage?

3. Will the labeling materials run, fade, abrade, corrode or age in a way that will damage the artifact?

4. Is the label readable?

5. Is it easy to find the label without having to handle the object a lot?

6. Is it easy to hide the label during exhibition or photography?  Is the label ugly?

7. What will happen if the label gets wet?

8. Is the label likely to come off with normal handling, running, or abrasion?

9. Is there a compelling and urgent reason to remove any existing labels that may be important to the history of the item? 

ANTLER, BONE, IVORY, TOOTH

  • Beware, sometimes synthetic materials are made to look like this.  See “PLASTIC”
  • Locate a smooth area that is not flaking, powdery or decorated.
  • Choose a location that will not show during exhibit or photography.
  • Apply base coat of B-72, paper label, top coat.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

BALEEN, CLAW, HOOF, HORN

  • Beware, sometimes synthetic materials are made to look like this.  See “PLASTIC”
  • Locate a smooth area that is not flaking, powdery or decorated.
  • Choose a location that will not show during exhibit or photography.
  • Apply base coat of B-72, paper label, top coat.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

Sometimes the tag is the redundant label on a basket, sometimes it is the only label.

BASKETRY

  • Typically, the underside of a basket is labeled and the inside of the lid, if present.
  • Choose a location that will not show during exhibit or photography.
  • For baskets with very large elements, like cedar bark mats or bark containers, apply base coat of B-72, paper label, top coat.
  • For baskets with a finer weave structure, do not use adhesive but instead a small hanging tag sewn in between the weave with a needle that may pass through easily.
  • Use labeled bag/ box as redundancy and to reduce handling.

Redundant label on the folder means less handling for the item itself.

BOOKS and PAPER

  • Inside cover and reverse of title page are the common places to mark a book. Writing on the top outer corner means the book doesn’t have to be opened all the way.
  • Number is usually applied to the back upper right corner of a sheet of paper such as a document or a print/drawing/ watercolor.
  • Choose a location that will not show during exhibit or photography.
  • Avoid labeling in an area that already has information written there (price, owner’s name, signature, etc.)
  • Apply number with a #2 or HB pencil, taking care not to press hard enough to make indentations. Write on a firm surface.
  • Use a labeled bag/ folder/ box as redundancy and to reduce handling. Insert an acid-free paper bookmark with number in pencil at the top to fragile books.

CERAMIC

  • Typically, the underside of a ceramic is labeled unless it is unusually large or heavy, and then a place is chosen low on the “back” side.
  • Locate a smooth area that is not flaking, powdery, painted or decorated. The smooth, hard, shiny exterior of some pottery, called glaze, is made of glass and can be labeled.
  • Beware painted surfaces and do not mark or adhere onto them.  Do not mark break edges of sherds.
  • Choose a location that will not show during exhibit or photography. Do not obscure maker’s marks on base.
  • Apply base coat of B-72, paper label, top coat.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

It is possible to safely label leather and gut, but I consider it a more advanced skill set and generally recommend a paper tag.

FEATHER, FUR, GUTSKIN, LEATHER

  • Feathers of significant size may be labeled on the quill with a small font paper label.
  •  Most feather and skin artifacts have delicate surfaces and the removal of an adhesive label will leave a stain.
  •  Many feather and skin artifacts are connected to composite objects with other parts that may be labeled instead.
  • Some feather and skin items are sewn and a Tyvek label sewn through original stitch holes with white cotton thread may work, using the technique recommended for garments and textiles.
  • Stitch each end of the label so minimal snips are needed for removal.
  • No new holes shall be made. If no technique above will work, use a paper tag or label the enclosure.
  • Taxidermy is typically labeled with a tag around the leg, and also the mount support if present.

I like the collections management solutions offered by labeling a coin holder used for glass beads.

GLASS

  • Typically, the underside of a glass vessel is labeled.
  • Large beads may be labeled with a tag on a string.
  • Locate a smooth area that is not flaking, powdery or decorated. Do not mark glass that suffers from glass disease (weeping, crizzling, etc).
  • Choose a location that will not show during exhibit or photography. Small font size on paper label helps.
  • Apply base coat of B-72, paper label, top coat.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

I think B-72 loves metal more than any other material.

METAL

  • Typically, the underside of a metal item is labeled. If the metal item is very heavy, the “back” may be labeled instead.
  • Locate a smooth area that is not flaking, powdery, rusty, decorated, or coated. Musical instruments are often coated, for example.
  • Coins are usually not labeled directly. Edges may be labeled if large enough.
  • Choose a location that will not show during exhibit or photography. Small font size on paper label helps for smaller objects.
  • Apply base coat of B-72, paper label, top coat. Avoid artist acrylics and adhesives containing ammonia with copper or alloys with copper such as sterling silver.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.
  •  Jewelry may be especially difficult to label, even with tiny font size. Redundant tags are helpful.

Did I mention I love redundant tags to minimize handling?

PAINTINGS

  • The back upper right hand corner of a painting is a good place for the number.  Large paintings may be marked on diagonal corners.
  • Artworks are sometimes removed from frames, so the back of the painting support is the best location for marking. Select a section of the wooden stretcher or strainer, plain wood if available.
  • Avoid touching the back of the canvas corresponding to the painted area. Label the rigid edges or backing board if the support is not visible.
  • Apply base coat of B-72, paper label, top coat.
  • In addition, use a paper tag attached to the screw eye, D-ring or other hanging hardware. This allows a painting to be identified without excessive handling.
  • Collector and exhibition labeling/ marking on paintings has a long and important tradition.  Avoid removing old labels from the backs of paintings.

PHOTOS

  • Number is usually applied to the back upper right hand corner, in a non-image area along the edge.
  • For paper, apply number with a #2 or HB pencil, taking care not to press hard enough to make indentations. Write on a firm surface.
  • For photos made of plastic, use the blue photo pencil.
  • Sometimes, the right amount of dullness on a graphite pencil will also work on plastic but care must be taken not to scratch the plastic.  If the plastic has oily fingerprints, plasticizers, or coatings, pencil will not work well.
  • Use a labeled enclosure such as a bag or folder as redundancy and to reduce handling.

Acetone damaged all these plastics. Water-based labels often peel off too easily. I prefer tags for plastics.

PLASTIC

  • Many kinds of plastic are vulnerable to the solvent acetone used in B-72 labeling adhesive, so this adhesive should not be used.  Some older plastics are sensitive to water-based adhesives.
  • It can be difficult to identify specific plastics.  Rubber, vinyl, plastics, and synthetic materials should be marked with great caution as removal can cause damage.
  • Adhered labels often pop off of flexible plastics.
  • Many plastic items are connected to composite objects with other parts that may be labeled instead.
  • For a completely plastic object, the most conservative recommendation is to only use a paper tag with a labeled bag/ box as redundancy.  Enclosures also reduce handling, and many plastics age poorly so the less handling the better.
  • Some museums use water-based acrylic adhesive labels, or B-67 in petroleum distillates, but removal of these labels is not risk-free.

This Melvin Olanna marble sculpture (ASM 2000-6-2) is heavy! Don't put the label underneath, or you risk damaging the artwork or yourself looking for it.

STONE

  • Typically, the underside of a stone item is labeled. If the stone item is very heavy, the “back” may be labeled instead.
  • Locate a smooth area that is not flaking, powdery or decorated. Porous or rough surfaces are difficult to label. Avoid use edges of stone tools.
  • Choose a location that will not show during exhibit or photography.
  • Apply base coat of B-72, paper label, top coat.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

Blank Tyvek tag showing loops at the ends that are easy to snip for removal.

 

These are labeled at the inner back of the collar, but a redundant tag on the hangar reduces handling.

 

For rolled textiles, redundant tags are really needed.

TEXTILES and GARMENTS

  • For textiles robust enough and large enough to hold a label, a sewn technique with Tyvek and white cotton thread is recommended.
  • Garments are typically labeled where a manufacturer’s label might be found, such as at the back of a neck or the waistband.  Labeling diagonal corners is helpful for large rolled textiles.
  • Choose a location that can be hidden during exhibit or photography.
  • Cut a piece of Tyvek, write the number by hand with a Zig Millenium fade-proof and waterproof pen in the center, leaving room for stitches at each end.
  • Use seams and original stitch holes whenever possible. Second best is to pass the needle between the weave without piercing the yarns.
  • Stitch the label with a loop through two holes at each end so minimal snips are needed for removal.  Sharp needles work well to pierce Tyvek, while ballpoint needles are less likely to damage the textile fibers.

Each rattle also has its number written in pencil on the pallet that holds it.Redundant paper tags in each dish reduce handling and facilitate locating an item.

WOOD

  • Wood items are often painted, varnished or otherwise coated.  Avoid applying a label to those areas and seek out an inner, underside, or back surface that is bare wood.
  • Locate a smooth area that is not rough, splintery, or decorated.
  • Choose a location that will not show during exhibit or photography.
  • Apply base coat of B-72, paper label, top coat.
  • #2 or HB pencil may also be used on wood if the number can be applied without denting the wood and if it may be removed again with an eraser. Pencil, however, tends to be harder to read.
  • Use paper tag, labeled bag/ box as redundancy and to reduce handling.

Collections Labeling: Alternate Adhesive Testing

November 25, 2011

 Ellen Carrlee (Conservator Alaska State Museum), Anna Marie Weiss (student, Queen’s University) and Samantha Springer (Conservator, Cleveland Museum of Art)

1. INTRODUCTION:

B-72 is the adhesive conservators recommend for museum labeling of archaeological artifacts.  Postings on labeling basics and suggestions for assembling a labeling kit are also posted on this weblog.  Properly done, the B-72 technique is legible, durable, reversible, and chemically stable.  However, the handling properties of the B-72 technique cause frustration, including unpredictable bubbling and the sensitivity of many inks to solvents in the adhesive.  There is great temptation to utilize other adhesives in pursuit of better handling properties, ease of application, and local availability.  As a follow-up to discussions at the 2010 Alaska Anthropological Association seminar on Collections Curation, several conservators independently tested several popular adhesive alternatives on bone, wood, metal, stone and unglazed ceramic to assess their performance.  Here are our observations, with some notes on our methodology if others want to test more adhesives.  Gallery of images at the end, you can click to enlarge.

2. SUMMARY:

Water-based adhesives had better handling properties for application.  These included ease of cleanup, single-step application, little odor or fumes, and the ability for the water component of the adhesive to penetrate the paper structure and cause it to drape and conform to uneven surfaces easily.  The thicker water-based acrylics and gels (those that were white and thick) also had the advantage of self-positioning easily.  The labels stayed where they were placed and did not move readily when brushed with a topcoat.  The thinner water-based adhesives tended to pool themselves up (from the water tension) when used on metal samples.  Among water-based adhesives, Golden Acrylic Gel had the best application properties of any adhesives tested.  However, many of these properties that are nice for the short-term convenience of the person applying the labels come at a long-term trade off for the best interests of the artifact.  Some corrode metal, some come off easily in moist conditions, and some are hard to remove without damage to the artifact.

Solvent-based adhesives tend to be more difficult to apply.  Disadvantages to the person applying the label include stickiness, more complicated cleanup, possibility of smearing inks or bubbling, disagreeable odor or fumes, poorer ability of the paper label to conform to uneven surfaces, and tendency to slip around when placed and brushed with a topcoat.  Application with adhesive of higher concentration gave a better result in conforming to uneven surfaces and corners staying down, but has sometimes been reported to be associated with bubbling.  Using a different topcoat with a B-72 barrier layer made the labeling process take longer, required more elaborate cleanup, and petroleum-distillate based topcoats were sticky, smelly, drippy and took a long time to dry.  However, the solvent-based adhesives tended to be better for survival of the label and removability without damaging the artifact.  To put it bluntly, the trade-off is: ease of application for the human comes at the cost of optimum preservation of the label and artifact.

3. RESULTS

PARALOID B-72 (ACRYLOID B-72)

B72 (marketed as Acryloid or Paraloid B-72) is a solvent-based acrylic resin.  It was tested in both reagent grade acetone and hardware store acetone.

PROS

  • Good aging properties, does not yellow
  • Pure formulation
  • Good durability in flood or high RH
  • Minimal staining after removal
  • Readily reversible with solvent
  • Hardware store acetone less likely to smear inks (likely due to impurities)
  • Reasonably neutral pH around 5-7
  • Paper label alone remains slightly flexible, adhesive film cracks a bit

CONS

  • Not locally available
  • Solvent fumes
  • Flammable
  • Can be sticky, stringy, require practice to apply
  • Acetone can evaporate too quickly to fully manipulate label
  • May bubble unpredictably, with no obvious fix that always works
  • Hardware store acetone results in mottled look
  • Harder to apply on bumpy surfaces than water-based adhesives
  • Label does not always self-position well
  • Corners of label sometimes lifted, risk for snagging
  • Poorer adhesion to wood than other substrates
  • Can cause some inks to smear
  • Cleanup is not as easy as water-based adhesives

B-72 with Soluvar or Regalrez top coat

Because B-72 is such a desirable barrier layer, alternate topcoats were explored to solve the smearing problem.  Soluvar is made of acrylic resins B67 and F10 in petroleum distillates, used as a picture varnish.  Regalrez is similar, but made of low molecular weight resins in petroleum distillate.  While solving the smear issue, the alternate topcoats caused other frustrations.

PROS:

  • Good aging in general
  • Pure formulation
  • Good durability in flood or high RH
  • Minimal staining
  • Readily reversible with solvent
  • Does not make ink smear the way acetone-based B-72 can.
  • Does not bubble
  • Reasonably neutral pH around 5-7
  • Paper label alone remains slightly flexible, adhesive film cracks a bit

CONS:

  • Not locally available
  • Soluvar sometimes leaves drips on surface of artifact after applied
  • Lingering paint-thinner type odor
  • Flammable
  • Top coat makes paper translucent or mottled, hard to read on dark surfaces
  • 2 step application: B-72, dry, then topcoat
  • Soluvar / Regalrez stay sticky for more than 24 hours
  • Soluvar yellowed a bit during artificial aging
  • Corners of label tend to stick up, risk snagging
  • Stickiness of topcoat annoying
  • Cleanup is not as easy as water-based adhesives

At the Cleveland Art Museum, conservator Sam Springer reports that printed labels are first given a coating of Aquazol to prevent the ink from smearing.

At the Alutiiq Museum in Kodiak, Alaska, registrar Marnie Leist reports they use B-72 as a barrier layer and art store acrylic as the topcoat.

ART STORE ACRYLICS

Water-based acrylic media including Daniel Smith Acrylic, Golden Fluid Matte Medium, Golden Gel, Golden Self-Leveling Gel, Liquitex Gloss Medium, Liquitex Matte Medium were tested as examples of art store acrylics.  Golden Gel is used by several museums in Alaska.

PROS

  • Easy application and cleanup
  • Locally available
  • Does not bead up as much as Acrysol WS-24 or Aquazol
  • Tacky, so label stays put when topcoat added
  • Good on bumpy surfaces
  • Does not smear inks
  • Does not bubble
  • Paper label alone remains flexible

CONS

  • High pH (alkaline) Measured from 8 – 10 in our tests
  • Most contain ammonia
  • All can corrode metals, especially copper and Cu alloys (tuned adhesive green)
  • Proprietary (impure formulations, can change anytime)
  • Yellows with age
  • Removal by swelling with solvents, then rubbing off
  • Removal can cause surface loss, since it doesn’t dissolve but swells
  • In flood/ high RH tended to become gummy and white, sometimes peeled off

RHOPLEX

Because water-based adhesives are more user-friendly than the solvent-based adhesives, conservation-grade water-based acrylic adhesive Rhoplex (also marketed as Primal) 33 or its replacement B-60-A was tested as an alternative to B-72 and art store acrylics.  Rhoplex is often used as a stone and plaster consolidant. Note that WS-24 is a different product.

PROS

  • Easy application and cleanup
  • Good on bumpy surfaces
  • Good aging
  • Pure formulation
  • Good durability in flood or high RH
  • Does not smear inks
  • Does not bubble
  • Paper label alone remains flexible

CONS

  • Not locally available
  • Cannot ship in freezing weather (product will be ruined)
  • High pH (very alkaline) Measured around 9-12 in our tests
  • Can corrode metal, adhesive turned yellow-green on aging.
  • Can yellow with age, saw some pink tinting around ink
  • Difficult to remove

ACRYSOL WS-24

Because water-based adhesives are more user-friendly than the solvent-based adhesives, conservation-grade water-based acrylic adhesive Acrysol WS-24 was tested as an alternative to B-72 and art store acrylics.  It is sometimes used as a consolidant for waterlogged archaeological bone.  Note that it is also sometimes sold as Rhoplex  or Primal WS-24.

PROS

  • Easy application and cleanup
  • Good on bumpy surfaces
  • Good aging
  • Pure formulation
  • Does not smear inks
  • Does not bubble
  • Reasonably neutral pH around 6-7

CONS

  • Not locally available
  • Can corrode metal (turned green-brown in aging test)
  • Can be watery when applied and label slips around
  • Yellows with age (more than other adhesive we artifically aged)
  • Weaker bond with age
  • Difficult to remove from porous surfaces
  • Paper label alone is brittle, cracks and shatters easily when flexed

AQUAZOL

Because water-based adhesives are more user-friendly than the solvent-based adhesives, conservation-grade Aquazol (a non-acrylic water based plastic) was tested as an alternative to B-72 and art store acrylics.  It is soluble in either water or alcohol.  It is commonly used as a paintings consolidant.

PROS

  • Easy cleanup
  • Good on bumpy surfaces
  • Good aging
  • Pure formulation
  • Does not smear inks
  • Does not bubble
  • Reasonably neutral pH around 5-7
  • Paper label alone remains flexible

CONS

  • Not locally available
  • Falls off readily in flood test
  • Messy and sticky to handle
  • Gets sticky or falls off in high RH (80%)
  • Corroded metal in some tests (adhesive turned green)
  • Can be watery when applied and label slips around

AYAF

AYAF is marketed pre-mixed as “PVA Marking Varnish” by MuseuM Services Corporation.  AYAF is a solvent-based polyvinyl acetate (PVA) resin equivalent to the European products Mowilith 50 and Vinylite A.  It is most often used as a consolidant for various materials.

PROS

  • Pure formulation
  • Reasonable aging properties (not as ideal as B-72)
  • Does not smear inks
  • Does not bubble
  • Easer to apply than B-72, but with many of its benefits
  • pH 5.5 still in the OK range
  • Paper label alone slightly flexible, does not crack

CONS

  • Not locally available
  • Not as easy to apply and cleanup as water-based adhesives
  • Harder to apply on bumpy surfaces
  • Solvent fumes
  • Peels off easily in flood test

NAIL POLISH

Fingernail polish is still occasionally seen in obsolete museum practices.  It was tested here with expectation for poor performance to gauge other adhesives against a “known negative.”  I tested Sally Hansen “Hard as Nails”

PROS

  • Locally available
  • Easy application and cleanup
  • Does not bubble

CONS

  • Proprietary (impure formulations, can change anytime)
  • Yellows with age
  • Acidic pH of 2-3
  • Strong odor
  • Smears ink
  • Corners of label tend to stick up, risk snagging
  • Paper label cracks, tears when flexed

4. METHODOLOGY

ELLEN CARRLEE (Conservator, Alaska State Museum)

Substrates:

  1. Metal: Penny coins dating after the year 2000, fresh from normal use without pre-cleaning.
  2. Stone: Dark gray slate from a museum diorama.
  3. Ceramic: Plain terracotta flowerpot, had been in outdoor use one summer.
  4. Bone: Mammal, mainly beach finds.
  5. Tooth: Mammal, from the museum educational collection.
  6. Wood: Plain popsicle sticks from craft store.

Adhesives:

B-72 in reagent grade acetone

B-72 in hardware store acetone

B-72 in reagent grade acetone with Soluvar topcoat

B-72 in reagent grade acetone with Regalrez topcoat

“PVA Marking Varnish” (AYAF in alcohol)

Aquazol 500 in ethanol

Daniel Smith Acrylic Medium (at least 10 years old, in the lab supplies)

Rhoplex B-60-A

Acrysol WS-24

Golden Self Leveling Gel

Golden Gel

Sally Hansen “Hard As Nails” nail polish

Abuse:

The tests involved submersion in a vat of water over a weekend (to simulate a flood incident), sealing in a bag at 80%RH for 24 hours, aggressively shake samples of each substrate together in a ziplock bag, aggressive abrasion with a dry toothbrush, and heating in an oven.  pH tested by adding a drop pHydrion pencil in solution to the wet adhesive Insta-check pencil “lead” dissolved in boiled, distilled water (see Odegaard, Carroll, Zimmt 2000).  Strip of pure copper painted with adhesives as a separate test for copper corrosion.  Tested paper label dipped in adhesive alone for durability.

Removal:

Removal techniques tested were dry scalpel removal (also called “mechanical” removal), water on a cotton swab, and acetone on a cotton swab.

ANNA WEISS (conservation graduate student, Queen’s University)

Substrates:

  1. Metal: pennies
  2. Stone: dark, fine grained stones from Lake Ontario beach
  3. Ceramic: terra cotta flowerpot (new)
  4. Bone: study samples from local archaeology group
  5. Wood: blocks of pine lumber

Adhesives:

B-72 in reagent grade acetone

B-72 in hardware store acetone

B-72 in hardware store acetone with Soluvar topcoat

Aquazol 500 in water

Rhoplex 33 (aka Primal)

Aquazol WS-24

Liquitex Acrylic Gloss Medium and Varnish

Liquitex Matte Medium

Abuse:

The tests involved submersion in a vat of water for two hours (to simulate a flood incident), sealing in a bag at 80%RH for 72 hours, aggressively shake samples of each substrate together in a ziplock bag, aggressive abrasion with a dry toothbrush, accelerated aging in over for 4 days to simulate 12 years, pH testing with pH strips using dried label mashed in water.

Removal:

Solvent removal with cotton swab, poultice or solvent gel, mechanical removal with scalpel, bamboo stick or dental tool.

SAMANTHA SPRINGER (Assistant Conservator of Objects, Cleveland Museum of Art)

Substrates:

  1. Metal: brass sheet
  2. Stone: smooth fine grained stones from museum campus
  3. Ceramic: terra cotta flowerpot (new)
  4. Glass: pyrex glassware
  5. Wood: pine 2 x 4 scrap wood

Adhesives:

B-72 in reagent grade acetone using Aquazol-coated label

Golden Polymer Medium Gloss

Aquazol 500 in water with B-72 topcoat

Rhoplex WS-24 Acrylic Dispersion (sprayed, reactivated with isopropanol)

B-67 in reagent grade Naptha (petroleum distillate)

B-67 in reagent grade Naptha using Aquazol-coated label

B-67 in acetone using Aquazol-coated label.

For some tests, the “Aquazol-coated label” was first spray-coated with two coats of 12% Aquazol 200 in reagent grade ethanol and allowed to dry.  This is to prevent smearing of the ink.

Abuse:

The tests involved submersion in a vat of water for two hours (to simulate a flood incident), sealing in a bag at 80%RH for 72 hours, aggressively shake samples of each substrate together in a ziplock bag, aggressive abrasion with a dry toothbrush, accelerated aging in over for 4 days to simulate 12 years

Removal:

Solvent removal with cotton swab, poultice or solvent gel, mechanical removal with scalpel, bamboo stick or dental tool.

5. THANK YOU!

Big thanks to our Alaskan museum colleagues and to the folks who discussed this with us on the American Institute for Conservation Objects Specialty listserve.  Apologies if I miss your name, but here’s my best shot: Helen Alten, Barbara Applebaum, Victoria Book, Scott Carrlee, Chris del Re, Dave Harvey, Katie Holbrow, Rick Kerschner, Steve Koob, Marnie Leist, Susan Lansing Maish, Katie Myers, Teresa Myers, Steven Pickman, Dennis Piechota, Monty Rogers, Linda Roundhill, Patrick Saltonstall, Monica Shah, Tony Sigel, Julie Unruh, and Jim Whitney.

Questions? Ideas? Feedback?  Ellen.Carrlee@alaska.gov


Light Fading From UV

November 5, 2010

This plain paper folder was placed in a window with southern exposure at the Alaska State Museum for two months.  The far left side was covered with aluminum foil to block out all light.  The middle third was covered with UV filtering plastic film.  This film was tested with a UV light meter to insure it was effective at blocking ultraviolet light.  The far right hand side of the paper folder was left completely exposed.

On my computer monitor (and on the real folder) you can see a slight difference in the faded blue color between unfiltered and filtered, but both are drastically faded from the section that was not exposed to light at all.  Hopefully this is evident on your computer monitor as well.   

While filtering UV light does eliminate a dangerous wavelength of light that is contributing to deterioration beyond just fading, if you seek to prevent the visual change of your colors from light fading, UV filtering will not give you the protection you need.  All light is damaging, and fading is cumulative and irreversible.  To prolong the vividness of colors, you must bring light levels down and limit overall exposure, not merely filter for UV light.


TEMP AND RH REVIEW FOR MUSEUMS 2010

October 21, 2010

PEM2 datalogger and HOBO Pro Series logger

A Review of Recent Ideas and Annotated Bibliography

Ellen Carrlee, Alaska State Museum Conservator, October 2010

 INTRODUCTION

For a long time, the climate ideal for museums was 50%RH and 70F with very little fluctuation.  This has been problematic because it costs money and fossil fuels to achieve that target, and many buildings simply cannot achieve it.  In addition, there have not been enough scientific studies on real materials to prove that this is the correct target.  The new way forward in thinking about museum climate involves an understanding that deterioration happens by different mechanisms (biological, chemical, mechanical) and that you have to balance the risks and benefits for each on.  Very low RH slows down biological and chemical risks, but increases risk of mechanical damage, for example.  The beginnings of a shift in our conception of appropriate collections preservation climate began in the mid 1990’s, but it has taken longer to reach the dawning of a new era.  A review of the recent literature suggests that a summary of the subject can be split into three areas: causes of damage, methods of analysis, and recommendations by material.

In thinking of the needs of a future integrated facility for the Alaska State Library, Archive, and Museum, I am struck by how the library/archive needs are really quite different from the museum needs.  To oversimplify, I think it is because the threats to paper are mainly biological and chemical, and therefore they are less concerned with RH and more concerned with temperature.  In general, they need RH to be lower than we like it at the museum, and fluctuations are not as threatening.  Our museum, with lots of paintings and organic ethnographic materials, is keen to have a bit more RH.  There are competing needs that have to be weighed.  Light fading risk goes down at low RH, but fracture risk goes up.  Higher temps reduce RH and therefore help prevent mold but low temps reduce chemical self – destruction.  Just as we’ve looked at light fading risk and recommended light levels for different categories of materials, we’ve started to consider temp and RH needs based on materials.  But that’s another posting (and a lot more reading for me!)

CAUSES OF DAMAGE

  1. Biological
  2. Chemical
  3. Mechanical/ Physical

Some people will say that RH is more important than temperature, and others will say just the opposite.  Seems like the answer depends on what kind of damage you want to prevent.  If it is biological, you need to keep your RH low.  There is an easy-to-remember rule of thumb that mold tends to flourish if you have stagnant air in a dark place over 70% RH and 70F for at least two days.  Also, insects and pests need moisture to live.  So for the biological risk, looks like temperature has the edge.  Chemical usually refers to rate of deterioration, like things becoming more acidic or corrosion happening.  It is hard to say if temp or RH is more important here.  Some sources will say that for approximately every 5C DROP in temperature, you double the life of your artifact.  Anyone remember the Arrhenius Equation from chemistry class?  That one says for every 10degrees C the rate of a chemical reaction doubles. Think about how fast sugar dissolves in hot tea and how slowly it dissolves in iced tea.  So temp is definitely important for those chemical reactions that cause degradation, but a lot of those equations involve water.  So RH is important, too…metal corrosion, dye fading, lots of things.  For chemical changes, short fluctuations in temp/RH don’t matter much, it is the situation over the long haul that is most important.  In general, room temperature is too warm for ideal long-term preservation of most organic materials as well as paper, leather, dyes, and film.  Mechanical damage seems to really connect strongly to RH and damage from movement caused by shrinking and swelling as moisture content goes up and down.  Now some of that risk is influenced by how brittle something is, and things get more brittle as they get colder, so temperature has a role, too, but not quite as much as RH.  Some sources separate out “physical” as another category to show how something might get torn apart because there are various materials all restrained in association with each other (composite or mixed-media), like drums or paintings, but this seems to fit OK in the “Mechanical” category.  James Reilly has a good description: To avoid mechanical damage, stay in the 20-70% RH range and keep outside excursions as short and infrequent as possible.  Seasonal extremes are worse than short-term events.  Short term excursions don’t matter as much because materials take quite a while to equilibrate, weeks and not hours or days.  The Smithsonian folks are more conservative with RH and in general suggest 30-60% as being OK for most collections.

METHODS OF ANALYSIS

How do they know what is really causing damage?  How do we know that damage didn’t just happen before it even came into the collection, or as a result of inherent vice in the material itself?  Apparently, those original targets of 50% and 70 degrees F were based on trying to replicate conditions of a slate quarry in the UK where valuable collections of the British Museum were kept during WWII, and the allowable fluctuations were based on the limitations of the HVAC equipment at the time.  When I was in school (late 1990’s) I was taught that what we really wanted was to keep that line on the hygrothermograph as flat as possible, and that big, rapid fluctuations were really bad for the artifact.

Proofed RH fluctuations Michalski the idea in a nutshell is that you look at the highest and lowest extremes of RH the object has been exposed to in the past, and then you avoid ever getting to that boundary again.  Whatever damage happened at that limit has happened, and as long as you stay away from that extreme, you’ll probably be OK.  Let’s say there was a crack in a wooden item that happened at low RH.  If you keep away from that extreme, the crack will probably just open and close with RH fluctations without getting any worse.  If you get closer to the extreme, the number of times that crack can open and close without consequence is limited.  Remember, this is just for mechanical damage.  That’s not the case for biological or chemical damage at all.  Also, conservation treatments may erase that proofed RH because they introduce new materials  and stress distribution in the object.  I have especially seen this in the treatment of large organic materials like kayaks…they show no major change for years before conservation treatment, and then in the year or two following treatment you see changes.  If the treatment was done right, those will result in the repairs opening up or flexing and not in new damage to the artifact.  I’ve come to think of these artifacts as experiencing a “period of convalescence” after treatment.

Isoperms Don Sebera’s work in the early 1990’s, looking into relationships between temp, RH and preservation as a matter of activation energies for decay reactions.  Quantitative graphical measures of relative permanence, such as if paper will last 100 years at the accepted standard, it will last only 3 years at 95F and 80%RH, but 1200 years at 50F and 40%RH.

IPI decay metrics  the Image Permanence Institute (a non-profit research lab at the Rochester Institute of technology) has done amazing work (grant funded by the NEH, the Mellon Foundation and IMLS.) to quantify things.  Great quote from James Reilly: “One cannot manage what cannot be measured”  An important aspect of this new way forward is to realize it is based on algorithms, modeling, predictions and other scientific ways of guessing how materials are supposed to behave.  Since deterioration mechanisms of each material are complex and dynamic, it is difficult to get real info about damage to real artifacts.  The whole IPI scheme is a great hypothesis, and maybe the best one we’ve got, but there is precious little in hard data and proof.  For each of the three forms of RH/ temp deterioration, they’ve picked something to be the canary in the coal mine and then projected possible damage to vulnerable organic materials using math.  Biological decay is predicted by mold growth, chemical decay is predicted by a model of deterioration for organic materials based on the hydrolysis of cellulose acetate (common plastic used for photographic film), and the physical decay is predicted by the equilibrium moisture content for an imagined block of wood from an “average species.”  Tim Padfield has a good article describing the science behind the preservation index and the TWPI http://www.conservationphysics.org/twpi/twpi_01.php

The Marvelous Marion Mecklenberg  OK, I have to be uber-caffeinated to read anything he writes, but the man has done great work, co-authored with many really stellar people and in general, when I think of cold hard data I think of Dr Mecklenberg and his colleagues,  in particular Tumosa, Erhardt, and McCormick-Goodhart.  They did research starting in the early 1980’s to measure dimensional changes to different materials with mechanical testing to predict stresses and strains, as well as modeling to show how much climate change was required to cause irreversible changes.  In 1994, they announced new guidelines for museum climate, suggesting that 50 +15% moderate fluctuations were OK, and that for general collections, 30-60% RH was mechanically safe.  Temperature in the human comfort range was fine, but avoid going below 13C (55F) due to some materials undergoing phase change and getting brittle, like acrylics.  Of course, some materials need more stable environments, like degraded materials, drums, veneers etc.  The current Smithsonian guidelines as of publication were 45 +/-8% RH and 70 +/-4F. 

ANNOTATED BIBIOLGRAPHY

My understanding of the current trend is based on the articles below.  The links were good as of October 2010, but if they fail for you, just try googling them.

____________“Rethinking the Museum Climate”  (2010) Meeting, April 12-13, 2010 MFA Boston http://blog.conservation-us.org/blogpost.cfm?threadid=2227&catid=175

____________ “The Plus/Minus Dilemma: A Way Forward in Environmental Guideleines”  (2010)  3rd IIC Roundtable, 13 May 2010, Milwaukee Wisconsin at the AIC annual meeting  http://www.iiconservation.org/dialogues/Plus_Minus_trans.pdf

In addition to the balancing ideal preservation environment with the comfort needs of visitors and employees in the same spaces, there is growing influence of economic and environmental concerns (carbon footprint) since trying to maintain a rigid target is resource-intensive.  Loan requirements are more strict than many institutions can achieve, and institutions often ask that the borrower keep more rigid standards than the lending institution can manage.  We need to be more honest about what are actually able to pull off.  Michalski thinks a 10% fluctuation is OK  He thinks the biggest issue is mixed media or composite artifacts.  National Gallery of Canada is now going with 44% RH +/- 3% in winter and 50% +/- 3% in summer, with a year-round goal of 71F +/- 2%

American Society of Heating, Refrigeration and Air-Conditioning Engineers. (2007) Chapter 21: Museums, Galleries, Archives and Libraries. ASHRAE Handbook, Atlanta, GA

The 1999 edition included a section on Museums Libraries and Archives for the first time.  Revised edition in 2003.  Michalski was lead author for the T and RH section.  Next one due out in 2011 will probably include more about “proofed fluctuations.”  The introduction here describes threats in decreasing order of seriousness: light, RH, temperature, air pollution, pest infestation, shock/vibration, natural disaster, theft/vandalism and misplacing objects.  IPI preservation index is specifically mentioned.  Lots of detail and references cited in the sections regarding biological, mechanical and chemical damage.  Conservative RH for no mold to occur at any temp on collections is under 60%.  Mechanical damage section seems to point toward +/- 10% as being a maximum acceptable RH fluctuation, with damage being reported when the fluctuation was closer to 20%, especially on cracked cabinetry and paintings.  Chemical damage section focuses on acid hydrolysis of paper, photos and magnetic media and recommends cold and dry but without a specific range given.  Response times of artifacts suggest that anything under an hour is probably not an issue, such as a 15 minute HVAC cycle, as long as dampness is not promoted.  In the design parameters section, Class A is considered optimum for most museums, with AA being high in energy costs without a lot of benefit.  10% seasonal swing in RH and 5% short-term fluctuation is OK.  Temperature set between 59 and 77F. Constant air volume is recommended.  Variable air volume tends to have poor humidity control, inadequate airflow, maintenance disruption, leaks, and inflexibility and is not recommended for collections housing.  The next version of this handbook is expected to come out in 2011.  Most engineers and architects are familiar with temp and RH issues only though this handbook, and conservators are wise to be familiar with its contents.

Anderson, Maxwell. (2010) Revising the Gold Standard  http://www.theartnewspaper.com/articles/Revising-the-gold-standard-of-environmental-control%20/20549

Brief article for general audiences, written by the director and chief executive of the Indianapolis Museum of Art.  There are three considerations of RH: set point, allowable fluctuation, and seasonal adjustment.  Some discussion of where the old target standards came from.  IMA 50% +/-8% (6% per 24 hours) and 70F +/- 4 (2 per 24 hours) 

ANSI/NISO Z39.79-2001 Environmental Conditions for Exhibition of Library and Archive Materials.  American National Standard developed by the National Information Standards Organization. http://www.kb.dk/export/sites/kb_dk/da/kb/nb/bev/Z39-79-2001_Udstillingsstandard.pdf

Set point for temperature should be below 72F with a variation of up to 5degrees on either side of your set point.  RH set point should be between 30 and 50% with a variation of up to 5% on either side of the set point.  Seasonal drift is not to exceed 5% per month. 

Bizot Group draft Guiding Principles (Int’l Group of Organizers of Large-Scale Exhibitions)

This organization is made up mostly of directors of large museums, and these are the people who will ultimately decide what temp and RH limits are in loan contracts between museums, and therefore the key to the big game of chicken: who will change their standards first?  Will other institutions still lend to that daring pioneer?  The IMA has already taken a step toward less restrictive temp and RH limits.

Chicora Foundation (1994) “Managing the Museum Environment.” http://cool.conservation-us.org/byorg/chicora/chicenv.html

For each 14 F rise in temp, double the rate of deterioration for paper.  Humidity is more important than temp and should be controlled first.  In contrast to some other sources (Reilly 2008) this article advocates making the humidity the controlled factor and allow the temperature to fluctuate.  Aim for 40%-55% with a daily fluctuation of +/- 3% and 65-75F with daily fluctuation of +/- 5%.  These are not necessarily the ranges we are still talking about in 2010, but specifying how much fluctuation is allowed per day is helpful.  A timeframe needs to be included when you are talking about fluctuation.  Discussion of isoperms.  Really interesting section on the major HVAC components.  A Constant Air Volume System properly filters air and keeps flow to prevent stagnant pockets of air, as opposed to a Variable Air Volume system, which delivers heated or cooled air to each zone and is cheaper but creates humidity instability.  Hmmm, how much humidity instability I wonder?  Electronic controls are more responsive than pneumatic, and the controls ought to be in the occupied spaces and not within the ductwork itself.  I need to compare this to what ASHRAE 2007 says….

Conrad, Ernest A. (2007) “Climate Control Systems Design and Climate Change.”  Contribution to the Experts Roundtable on Sustainable Climate Management Strategies, held in April 2007, in Tenerife Spain.  http://www.getty.edu/conservation/science/climate/paper_conrad.pdf

Author has a master’s in environmental engineering and has been designing systems for major museums and libraries for 25+ years.  Apparently, mechanical engineers look at statistical weather data, mostly published by ASHRAE in 30-year averages since 1950.  Humidistatic heating often used in historic buildings where they don’t want to add in moisture…instead, they just drop the temperature to put RH in the appropriate realm.  Mentions the New Orleans Charter for Joint Preservation of Historic Structures and Artifacts (1990-91) which was apparently written to establish a philosophy regarding balance between protecting collections, historic building structures and comfort of occupants.  Thrust of the article was to discuss impact of a 1 degree C global increase in temperature.  Mostly it seems that the risk of high RH could increase from an expansion of the tropical zone, and more dehumidification would be needed, thus causing more pollution. Greater risks are associated with increased incidence of extreme weather.  While the author seems very expert in his own field, the topic of the article seems to be more about speculative effects of climate change, which is not his realm of professional expertise, and he doesn’t cite references.  

Conrad, E. A. (1996) “Environmental Monitoring as a Diagnostic Tool.” In Preservation of Collections: Assessment, Evaluation, and Mitigation Strategies. Papers presented at the workshop, Norfolk, Virginia, June 10-11, 1996. Washington, D.C.: the American Institute for Conservation of Historic and Artistic Works. pp. 15-20.

Conrad, Ernest A. (1995) Balancing Environmental Needs of the Building, the Collection, and the User. East Norwalk, CT: Landmark Facilities Group.

Erhardt, D., C. S. Tumosa and M. F. Mecklenburg, (2007) “Applying Science to the Question of Museum Climate.” In Museum Microclimates, Contributions to the Copenhagen Conference, 19 – 23 November 2007, ed. T. Padfield and K. Borchersen. National Museum of Denmark, 2007: 11-18.   http://www.natmus.dk/graphics/konferencer_mm/microclimates/pdf/erhardt.pdf

If you need to cut to the chase, read this article and then the ASHRAE chapter.  Lays out the history of the traditional standards, which had little scientific evidence and were best guesses and outside factors like limits of HVAC systems, buildings, or local climates.  The Boston MFA installed heating, air washing and humidification in 1908 and determined that 55-60% was the best RH for paintings.  Air conditioning technology improved, and by 1941 it was seen in the National Archives and Library of Congress, among other institutions. The WWII slate quarries in Wales so often mentioned used heating to achieve an RH of 58%, the average RH in the National Gallery of London from measuring the equilibrium moisture content of blocks of wood in the gallery. Some places like Canada used lower RH values (around 25%) because higher values were hard to maintain in winter. The idea that objects were “use to it” was used as justification without scientific proof.  There is also a prevalent notion that more constant is better, although the +/- 2% fluctuation sometimes dictated is hard to even measure accurately with the methods we commonly use.  “Specifying climate control requirements and telling the engineers to implement them is easier by orders of magnitude than the research required to justify the specifications.”  Mecklenberg and his colleagues, in particular Tumosa, Erhardt, and McCormick-Goodhart) did research starting in the early 1980’s to measure dimensional changes to different materials with mechanical testing to predict stresses and strains, as well as modeling to show how much climate change was required to cause irreversible changes.  In 1994, they announced new guidelines for museum climate, suggesting that 50 +15% moderate fluctuations were OK, and that for general collections, 30-60% RH was mechanically safe.  Temperature  in the human comfort range was fine, but avoid going below 13C (55F) due to some materials undergoing phase change and getting brittle, like acrylics.  Of course, some materials need more stable environments, like degraded materials, drums, veneers etc.  The current Smithsonian guidelines as of publication were 45 +/-8% RH and 70 +/-4F. 

Grattan, D. and S. Michalski, (2010) “Environmental Guidelines for Museums – Temperature and Relative Humidity (RH).” Canadian Conservation Institute. October 2010. www.cci-icc.gc.ca/crc/articles/enviro/index-eng.aspx

Current trend away from a target and toward embracing a range.  Linking RH fluctuation to measurable damage.  Cooling makes RH go up, warming makes RH go down.  Damage is three kinds: biological, chemical, and mechanical.  Fluctuation is the main threat, and your “class of control” defines the allowable degree of fluctuation.  Libraries and archives ought to keep things cool as long as it is not too damp.  Around 30% RH or less.

Hughes, Susan.  UK National Archives, Conservation DistList posting July 15, 2010

The British Standard Institution (BSI) is working on new standards packaged as Publicly Available Specification (PAS 198) for environmental conditions in museums libraries and archives, which will influence storage, display, and loans in the UK.  Expected out in May 2011.

Image Permanence Institute (2005) Step-by-Step Workbook: Achieving a Preservation Environment for Collections.  Image Permanence Institute, Rochester Institute of Technology.  Rochester, NY August 2005

As opposed to the “target” set point recommended for many years, the new way forward in temp/RH involves an understanding that deterioration happens by different mechanisms (biological, chemical, mechanical) and that you have to balance the risks and benefits for each one…very low RH slows down biological and chemical risks, but increases risk of mechanical damage, for example.

They have a holistic approach to the preservation environment, which includes a Preservation Management Process: 1. Understand 2. Evaluate 3. Take Action.  As part of understanding, it includes recommendations for how to understand your own HVAC system.  The ”schedules” section of mechanical plans are the part you want.

Great explanation of the importance of dew point.  The temp at which water will condense out of the air, so it is a measure of the absolute amount of water in the air.  If you have that amount of water outside when it is cold, the RH will be pretty high, but then bring it in and warm up the air and the RH goes down.  An example I looked up for rainy Juneau Alaska: if it is 40F and 90%RH outside, that’s a dewpoint (absolute amount of water) of 37.  Take that inside and heat it up to 70F, you get an RH of only 30%.  Also of interest: materials change temperature very quickly, in less than a day.  But it could take weeks or months to equilibrate to changes in RH (faster at higher temps, though.)

An important aspect of this new way forward is to realize it is based on algorithms, modeling, predictions and other scientific ways of guessing how materials are supposed to behave.  Since deterioration mechanisms of each material are complex and dynamic, it is difficult to get real info about damage to real artifacts.  This implies that the whole IPI scheme is a great hypothesis, and maybe the best one we’ve got, but there is precious little in hard data and proof.  For each of the three forms of RH/ temp deterioration, they’ve picked something to be the canary in the coal mine and then projected possible damage using math.

Biological: Measured by the Mold Risk Factor. Number 1-5, with anything above 1 indicating mold growth. Mold growth as a problem above 65%RH.  Spores won’t germinate below that, or if the temp is below 36F.  Germination happens in two days under favorable conditions (86F is ideal) but three years or more in marginal conditions.  Estimates came from published mold studies on stored food grains, and then mathematical modeling by Doug Nishimura of IPI and models from Stefan Michalski of CCI.  Higher temps also mean insects eat more and breed faster.

Chemical: Measured by the TWPI.  Higher numbers are better.  Temperature and humidity are the “speed controls” on natural aging, and they also combine with other agents of deterioration to accelerate decay.  “Deterioration is cumulative and progressive, and it doesn’t reverse itself when conditions improve.”  Example: milk doesn’t un-spoil when you put it back in the fridge after leaving it out for a few days.

Physical:  Measured by “dimensional change metrics” (shows up as EMC on software) with 2.5% or higher being bad.  They are estimating this aspect of deterioration from the behavior of an imagined block of wood from an “average species.”  Unclear what that means, really. 

 

PEM Preservation Environment Monitor.  Name of the IPI’s dataloggers.  Cost about $350 each in 2010.

Climate Notebook software sold that reads and interprets data from various loggers.

Preservation Index  (PI) Suggests, in years, how long it will take for a vulnerable organic material to become noticeably deteriorated under the conditions given.  Higher number (over 50) is good, with very good environments up around 200.

Time-Weighted Preservation Index (TWPI) A quantitative model of organic decay, tries to give an idea what is going on over a longer period with fluctuating conditions.  Higher number (over 50) is good, with very good environments up around 200.

Preservation Calculator: You enter temp and RH, it tells you the rate of natural aging from chemical change, and risk of mold for organic materials in general.  It gives you a PI number, too.

Dew Point Calculator: You can calculate temp, RH or dew point if you know two of the three.  Then it tells you the PI, mold risk and mechanical damage risk.  Using this helps know if your mechanical systems are humidifying or dehumidifying.  Also, IPI says keeping summertime dew points low is one of the most important factor of all in preservation.  If dew point is high outside, just cooling the air isn’t enough.  If you just cool it without taking water out, your indoor RH is way too high.

Equilibrium Moisture Content: Amount of moisture in a material at certain RH.  Above 2.5% in the Climate notebook interpretation indicates dangerous dimensional change.

Mecklenberg, M.F.  (2007) “Determining the Acceptable Ranges of Relative Humidity and Temperature in Museums and Galleries.”  Smithsonian Museum Conservation Institute 2007. 

2004 Smithsonian standards were around 45% RH +/- 8% and 70F +/- 4degrees.  Part one of the article is 57 pages on structural response to RH and part two is 29 pages on structural response to temperature.  In a nutshell, it seems that most materials are OK in the RH range of 30-60%, with 30-37% and 53-60% being cautionary regions.  For temperature, above 74F gets into increased chemical activity and should be avoided.  Down to around 55F is OK also, but below that we get into the glass transition temperature of many materials (acrylic paint has a Tg around 50F) and therefore risk brittleness and cracking.  A lot of this research involves paintings and wood.

Michalski, Stefan  (2007) “The Ideal Climate, Risk Management, the ASHRAE Chapter, Proofed Fluctuations and Toward a Full Risk Analysis Model”  Contribution to the Experts’ Roundtable on Sustainable Climate Management Strategies, April 2007, Tenerife Spainhttp://www.getty.edu/conservation/science/climate/paper_michalski.pdf

“Proofed RH or T” is the largest fluctuation to which an object has been exposed in the past.  Risk of further mechanical damage from fluctuations that are smaller than the proofed value is low.  Ie, once the crack happens, it just opens and closes and doesn’t tend to get worse, especially if you stay away from those past extremes.  This is for mechanical damage.  Mold, chemical aging different.  When can repeated stress be handled indefinitely?  For tough materials, at about ¼ the stress that causes the damage can be repeated over and over OK.  For brittle stuff, about 1/10th.  So the safe zone is smaller than the proofed zone.  But even a little below the proofed value means there are many cycles needed.  Go straight to risk assessment based on past climate records.  Furniture, paintings other mixed collections susceptible to fracture from fluctuations: the worse their past the better their future.  “previous fluctuation history”  Response times of the objects?  Extreme fluctuations are sometimes shorter than the response time of the material.  Conservation treatments “erase the safety margin achieved by the fractures from historical conditions.”  Light fading risk goes down at low RH, but fracture risk goes up.  Higher temps reduce RH and help prevent mold, low temps reduce chemical self destruction.  Many collections survive well in non-ideal conditions, and many museums who claimed to reach the ideal didn’t.  People want a specification to deal with reality rather than the ideal.  He’s working with ICCROM on web-based manual for risk assessment.  This idea of proofed fluctuations is also going to appear in the 2011 ASHRAE chapter?  The part that is problematic in my mind regarding proofed fluctuations is new incoming artwork and artifacts whose proofed fluctuation may be smaller than that of the collecting institution overall?

Michalski, Stefan (1994) “Relative Humidity and Temperature Guidelines: What’s Happening?” Canadian Conservation Institute Newsletter. No 14. September 1994 pp. 6-10

Some basic concepts: low temps can cause some materials to get brittle, while high temps can promote chemical deterioration of many materials, especially acidic paper, nitrate/acetate films, celluloid and rubber.  Each drop of 5 degrees C doubles the lifetime of an artifact.  High RH promotes mold, corrosion, deliquescence, and promotes degradation through chemical self-destruction.  In most Canadian museums, the “proofed RH” seems to be +/- 25%.  Keeping within 20% +/- is suggested as reasonable, (although other articles suggest that 20% is too great, and maybe 10% is more appropriate?)  Useful table “Effect of Incorrect RH and Incorrect Temperature on Museum Materials”  The Abbey Newsletter, Vol 18 No 8 Dec 1994 has a review of this article by Ellen McCrady, a book and paper specialist.  She said the article was accurate for paintings and objects, but weak in the realm of paper and photos. 

Ogden, Sherelyn. (2007) NEDCC Preservation Leaflet 2.1 Temperature, Relative Humidity, Light and Air Quality.  Basic Guidelines for Preservation.  North East Document Conservation Center. http://www.nedcc.org/resources/leaflets/2The_Environment/01BasicGuidelines.php

Deterioration doubles for every 18 F temperature rise.  Libraries and archives prefer RH 30-50%, the lower end of that the better.  Excessive fluctuations in RH can lead to dimensional changes, cockling, flaking inks, warped covers, and cracked emulsion on photographs.  She does not specify what fluctuation over what time period would be excessive.

Pacifico, Michele F and Thomas Wilsted.  (2009) Archival and Special Collection Facilities: Guidelines for Archivists, Librarians, Architects and Engineers.  Chicago.  Society of American Archivists.  

Padfield, Tim (2009) “Lecture on Archive Environmental Standards.” 

http://www.conservationphysics.org/standards/tp-cen-bsi.pdf

BS5454:2000 is the British Archive Standard, is difficult to enforce and seems rather arbitrary.  16-19C for handled stuff, 13-16C for stored stuff, and an RH 45-60% with a 5% fluctuation.  Science still cannot measure very slow deterioration.  Interesting historical and archaeological examples:

St Catherine’s Monastery in Sinai Egypt dates back to the 6th century.  RH 10-30%, temp 8-30C

Desert of Eastern Turkistan, 3rd century papers buried in sand in an abandoned building.  RH 30-50%, temp -10 to 25C

Padfield, Tim (2005) “How to Keep for a While What You Want to Keep Forever”

Respected scientist and consultant in the field of museum climates.  “The standard we have in conservation are particularly unconvincing and the evidence that supports them is shaky and controversial”

Padfield, Tim (2004) “The Preservation index and the Time Weighted Preservation Index”  http://conservationphysics.org/twpi/twpi_01.php

Article about the Image Permanence Institute’s standards for preservation storage environments.  “Preservation index” links temp/RH to chemical deterioration (as opposed to biological or mechanical) based on a study of the deterioration of a common photographic film, cellulose acetate, through hydrolysis.  “Time Weighted Preservation Index” is a way to indicate the situation taking the variation of the room over time.  Padfield explains the chemistry (law of mass action and Arrhenius law) for the degradation of the cellulose acetate reaction and how both temperature and RH impact it.  He has a slightly different interpretation of what is going on chemically than IPI does, but doesn’t seem to quibble with their product.

Rawlins, (1942) “The Control of Temperature and Humidity in Relation to Works of Art.”  The Museums Journal (Museums Association) 41: 51-90

Very early and influential text setting the standard at .  “Target “60F 60% 

Reilly, (2008) “Specifying Storage Environments in Libraries and Archives.”  From Gray Areas to Green Areas: Developing Sustainable Practices in Preservation Environments, 2007, Symposium Proceedings by the Kilgarlin Center for Preservation of the Cultural Record, School of Information, The University of Texas at Austin.  Published online: September 2008, http://www.ischool.utexas.edu/kilgarlin/gaga/proceedings.html

“One cannot manage what cannot be measured”  In contrast to some other articles (chicora 1994)  he advocates that temperature matters more than RH.  Like Michalski’s articles, Reilly explains the risks in terms of biological, chemical and mechanical damage.  This model is really helpful.  Biological damage (especially mold) happens with high RH, usually above 65 for a few days or more.  Chemical damage is accelerated with heat and moisture, and examples include corrosion, yellowing, embrittlement, and fading.  For chemical change, short term fluctuations don’t matter much.  Mechanical damage mostly relates to hygroscopic materials, and the damage would be cracks, deformations, delamination etc.  High RH causes hygroscopic materials to swell and soften, while low RH causes them to shrink and become brittle.  For avoiding mechanical damage, you need to stay between 20-70% RH and keep excursions outside that range as short and infrequent as possible.  Seasonal extremes are worse than short-term events because materials take considerable time to equilibrate…weeks or months, not hours or days.  Room temperature is too warm for ideal preservation of many organics, paper, leather, dyes, film, etc.

Ryhl-Svendsen, Morten, Lars Aasbjerg Jensen, Poul Klenz Larsen and Tim Padfield.  (2010)  “Does a Standard Temperature Need to be Constant?” Presented at the Going Green conference, British Museum, April 2009  http://www.conservationphysics.org/standards/standardtemperature.php

Article argues for allowing temperature fluctuation greater than traditional standards allow while keeping RH controlled.  Uses three institutions in Denmark as an example.  Royal Library in Copenhagen is about 65F and 50%, permanently air conditioned.  Arnamagnaean archive in Copenhagen University has buffered conservation heating, which allows the temperature to fluctuate as the outdoor temp fluctuates but keeps a steady RH.  Museum store in Ribe, Denmark has dehumidification only, with temp of 50-60F and a steady RH as long as the equipment is functioning properly.  When it does not work, RH reaches dangerous levels.  Ventilation is an issue, and the authors recommend recirculation of the inside air through a filter.

Sebrera, Donald K.  (1994) “Isoperms: An Environmental Management Tool”  Washington DC: The Commission on Preservation and Access  http://cool.conservation-us.org/byauth/sebera/isoperm/

Credited with being the first person to explore preservation, temp and RH relationships using a “kinetics model based soley on theory and assumptions about the likely activation energies of decay reactions.” (quote from the IPI Step-by-Step workbook)

Thompson, Garry. (1978) The Museum Environment  Butterworth Heinemann

Until recently, the contemporary standard for museum environment.  50% RH +/- 5% and 70F +/- 3 degrees.  Allowable fluctuation apparently based on the switching differentials of the best available HVAC systems of the 1970’s.  Part of the reason this book is so influential is that the author worked for the Scientific Department of the National Gallery, London and examined the available scientific evidence.  He also was aware that there was little proof for the limitations, and qualified his statements carefully.  He chose 55% largely as a midpoint between 70% risk of mold growth and the then-prevalent notion that below 40% organic materials become brittle 

Weintraub, Steven.  (2006) “The Museum Environment: Transforming the Solution into a Problem.”  Collections: A Journal for Museum and Archives Professionals Vol 2. No 3 (February 2006) pp 195-21