Pondering the Cleaning of Ethnographic Gutskin

Internal organ skins of marine mammals continues to be an area I find interesting and under-explored in the conservation literature.  Not long ago, several gutskin items came into the collection at the Alaska State Museum: two gutskin bags and one round hat.  The size of the skin strips and their physical appearance resembled materials often identified on artifacts as seal intestine.

Alaska State Museum 2008-10-1

The underside of the hat, both images are before treatment

The hat was recognized by the curator, Steve Henrikson, as quite special.  While made of traditional Alaska Native materials, it was a design typically seen in sailor’s caps such as those used by Russian and European seafarers.  Several hats of this kind can be found in one of my FAVORITE books, The Etholén Collection, which has many wonderful photos and descriptions of Alaskan artifacts in the National Museum of Finland.  The hats similar to this one are attributed to the Aleut.  Our hat had dyed wool tufts and remnants of feathers, as well as red and blue paint on the welting sewn into the seams.

The hat was among recent acquisitions selected for the summer 2010 Alaska State Museum exhibition “From Gift to Gallery.”  I recalled that in fall 2009, our intern Lauren Horelick noted that humidifying seemed to help release dirt.  She observed this during treatment of a pair of Aleut or Alutiiq boots made from a marine mammal internal organ tissue, possibly sea lion esophagus.  

Lauren Horelick working on boots from the Sheldon Jackson Museum collection, 2008-6-1

Lauren wrote in her report,  “After exhausting dry cleaning methods, aqueous cleaning began experimentally with distilled water on cotton swabs. Initially this did not appear to be an effective method, producing very minimal soiling on the swab. Perhaps this was due to a lack of applied pressure. However, after the boots were humidified (step 6) the use of a cotton swab and distilled water removed a significant amount of dirt. A 16-ounce can was eventually filled with completely blackened swabs after both boots were surface cleaned along the interior and exterior.  It is possible that the process of humidification swelled and loosened the dirt from the surface of the legging material. Humidity may have also relaxed the fibers sufficiently to release the soiling. The cleaning appeared to bring a more luminous quality to the boots with an overall brighter yellow color.”

Lauren manipulating the skin of the boot

After surface cleaning the hat with dry techniques, we undertook overall humidification of the hat in a humidity chamber.  I brought the chamber up to its practical limit of about 80% RH over the course of about four hours.  The method I like to use involves small containers of water with sponges in them to increase surface area, and after a couple of hours I soak a few strips of crumpled acid-free blotter with water and add those to the chamber to speed up the rate that the humidity increases.  The wet items are located below the wire shelf, so cannot come in contact with the object.  I need the object to get pliable, manipulate it and position it within the course of a single work day because I don’t want to leave gut material damp overnight.  The cotton textile lining got very limp, almost damp.  But the gut was not cooperative for very long, and I had a very short working time.  Maybe 10 minutes maximum before it was too stiff to manipulate without risk of new tears.  I wondered if I should have used some solvent for humidification, as sometimes the smaller molecule size of certain solvents is thought to penetrate better during humidification, but I was concerned about the pigments. 

Gutskin hat beginning humidification in the chamber

I inverted the hat and used small clips suspended from a hoop to encourage the rim back into shape.  The wooden clothespins were attached at intervals around the rim over small sections of curved (by curling) blotter paper on the interior and exterior of the rim.  Because the gut started to become brittle again, this was the extent of the re-shaping at the first pass.

First attempt to reshape the rim of the hat

A second overall humidification was repeated in the humidity chamber, following a similar humidification profile.  Put in at 8:30am and removed at 3:30pm, as the rim began to collapse again and take on memory of crumpled shape.  Stuffed out the outer areas of the hat with acid free tissue and inserted a cotton-covered disc of 1” polyethylene foam inside rim to help maintain shape.  The foam was cut smaller than the rim to leave space for strips of curled blotter to be clipped both inside and outside the rim again.  The foam was then placed on a riser so the clips could hang free and their weight could help encourage the rim into position.  A little extra weight was added to one side in order to even out the shape.  I did this with magnets attached to the springs of a few of the clothespins.

Reshaping the hat before wet cleaning

Now comes the interesting part, and I was grateful for the assistance and observations of Aurora Lang during this phase of treatment.  Aurora has a Museums Studies master’s degree, and was volunteering at the museum for a few months before she became the new Curator of Collections and Exhibits at the Cordova Historical Museum.  She and I agreed on our observations about the wet cleaning of gutskin. 

Some of this dirt had come off with a soft brush and a low-suction vacuum, but much still remained on the surface after dry cleaning techniques were done

The sooty dirt was not removed nearly as well with distilled water as it was with saliva.  Warm water works better than room temperature water, but not better than saliva (which also affords more control.)  On a scale of one-to-ten, with 10 being the best, the use of saliva is a 10, warm water is a 7 and cold water is a 3.  Warm water is at least twice as effective as cold water.  Saliva aids in the release of the soot, and repeated rubbing of the area is not needed as extensively it is with water alone.  Swab slides over the surface easier, and it feels a little more lubricated.  When water is used, the rubbing makes crinklier sounds and feels more aggressive.  Biologically, saliva and gut are quite compatible.  To what degree are we benefitting from enzymatic action?  Should we be worried about putting a bit of our own DNA on the surface? 

Lower left area is cleaned, the horizontal area has not yet been cleaned in this image

 Dirt continues to be released with repeated applications of saliva.  The best cleaning happens if you take two steps forward and one step back.  It seems that if you get the gut in one area to seem clean, and then you move on to another area and let the first one dry, more dirt comes to the surface in the first area, showing up as little islands of dirt in the crevices.  Cleaning a small area (approximately 2” x 1”) will take about 3-4 minutes on the first pass, and only about half that amount of time on the second pass which is most effective if done perhaps 2-4 minutes later.  This can be repeated a few times until the swab no longer comes away dirty.  On the first pass, the gut will get very pliable and soft, like pasta or perhaps like seaweed in miso soup.  The texture is delicate and it seems as if it might be punctured easily but we did not have that problem.  On the second pass, perhaps 4 minutes later, the gut feels supple under the swab but not pasta-like as on the first pass.  It is not crinkly and is still semi-humid.  It is in this state that a lot of dirt can be removed from the gut.  After cleaning, the gut has a semi-translucent luminous quality, almost glowing, that it did not have before cleaning.  Feathers and pigments were avoided.  Because we were concerned with the residues of the saliva cleaning, we went over all those areas one last time with cotton swabs dampened in ethanol.

From left-to-right: cleaned with saliva, distilled water, and warm distilled water

For comparison, cleaning was also attempted on the lined gut bag that was also part of this accession.  Since its construction and materials were similar and it came from the same accession, it is assumed that its manufacture and soiling history would be similar.  It was notably more difficult to remove dirt from the un-humidified bag, but cleaning could be done successfully with repeated passes.  More passes were required and dirt did not come off as easily.  From this we felt that perhaps Lauren was right and that our overall humidification of the gut made it easier to clean.

After treatment, top of hat

After treatment, gutskin hat, Alaska State Museum collection 2008-10-1


5 Responses to Pondering the Cleaning of Ethnographic Gutskin

  1. Lauren Anne Horelick says:

    Ellen, thanks for looking further into this topic! Its great.
    I am curious to know if other conservators working with cleaning gut have had similar observations.
    I love the solvent/ swab comparison. Is it possible that you have MIGHTY saliva?

  2. ozge says:

    Thanks for posting this Ellen. I had to treat some gut skin objects at the Southwest Museum. It is always good to see what others do. I have also been told that Natives spray gut skin objects wet to reshape.

  3. Luba Dovgan Nurse says:

    Ellen, hello, there is a very similar hat in shape and construction made from gut in the collection of the National Museum of Ethnology, Leiden, object id: 331-5, dated to 1882. The website http://www.volkenkunde.nl/collections allows to search. The text is in Dutch, I usually use Google translator. I have recently worked on a similar in shape hat but in basketry technique (Tlingit, 1880s).

  4. […] tissues on several artifacts quite perplexing.  Alaska State Museum has been pondering the unique properties of this material and its treatment as […]

  5. Ingrid says:

    This entry was very helpful! Thank you!

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