From: Neven Peko <[email protected]>
Subject: [Consdistlist] conservation of mammoth bone and tusk
Dear colleagues,
Do you have any idea how to consolidate [mammoth tusk] without using solvents
such as ethanol or acetone? We would prefer to use a water-based system because
of health risks.
Also, a large part of our mammoth bones collection was treated in sixties by
immersion in diluted PVA or PVAc glue (white thick wood glue). Do you have any
idea how to chemically remove it without affecting the very porous bone? Also,
do you have any suggestions on how to consolidate bone previously treated in
this manner?
Thank you all!
Neven
------------------------------
Neven,
While I'm not an ivory expert, here are my thoughts. Ivory tends to be
a pain to safely dry if it is found in a wet or high RH environment, though not
impossible. If it's stable it's potentially easier and safer to keep it in the
same environment, as you have, than anything else. Could it be displayed in a
tank of distilled or deionized water? Being a river, I'm guessing it was found
in fresh water which is a plus as salt water can cause delamination of ivory
materials and efflorescence when dried. Drying of waterlogged ivory can also
cause warping, splitting, etc. of the ivory if nothing additionally is done, or
even if it is. If you check the Consdistlist archives back in 1998 there was a
discussion about waterlogged ivory and controlled drying that may give you some
things to try. Ian Godfrey from, at that time, the West Australian Museum is
noted as carrying out a study on drying waterlogged ivory. It appears he has
retired but seems to still be active as a conservator/researche
r. If you're able to safely dry the ivory after speaking with some people that
have experience in that area you may have much better luck and more options for
consolidation than working with it while wet.
If drying isn't appropriate you may want to look into options utilising
polyethylene glycol (PEG) as this is often used for waterlogged materials. I've
seen note of employing silanes in such situations I believe (a similar process
is noted here for with regards to stone and alkoxysilanes, I haven't read
through the whole thing but it seemed to be the most relevant source I could
come across:
https://www.getty.edu/conservation/publications_resources/pdf_publications/pdf/alkoxysilanes_vl.pdf).
A 'silane treatment' can also be combined with an acrylic resin if the surface
is particularly friable to give a greater adhesion, how this would work with
waterlogged items would need to be investigated. Depending on your specimen you
may not have the greatest result due to the density of ivory versus other
similar materials with either of the above options. One thing to note, if the
piece is purely a display item with little research value a consolidation
treatment isn't an issue. If the piece
is noted as having research value consolidation should be avoided as this can
reduce or eliminate the ability for researchers/scientists to work with this
particular item and obtain useful information. One compromise if you need to
remove it from the bath would be to work on the majority of the item but leave
a small part untreated, even if the untreated part cracks, so that testing and
research could be carried out without issue. All that being said, many small to
medium sized general history museums likely wouldn't be able to carry out the
above treatments in-house for reasons of equipment or cost. Possibly a national
level museum has access to or the ability to carry out such treatments. As
mentioned above, if you're able to carry out a controlled drying your in-house
consolidation options will expand and see costs lowered.
PVAC has been used for bone consolidation in the past so it's not
surprising you have mammoth remains treated in this way. It could also be
another 'white glue' but that's hard to say unless you have well documented
records so you may choose to go ahead with assuming it's an unknown. Depending
on the scale and condition you may choose to consolidate as is or remove the
previous consolidate and consolidate anew. The number one thing I'd say is
don't immerse the bones in water or employ a humidification setup in an effort
to loosen or re-adhere the consolidate; dry bones and water/considerable RH
increases they don't mix well. A conservator with experience in treating bones
may have a reasoning after seeing the items in person for submersion of dry
bones but it's not something to be done without proper experience. A national
museum in Croatia might be able to give some specialised advice or you can
trying contacting the Croatian Conservation Institute or the Canadian
Conservation Inst
itute. If you want to try taking off the consolidate, try spot testing with
water and see if the material on the bones is soluble. If it is, great. Work a
small area at a time with a minimally damp swab and even drying the spot with
some cotton immediately after. As you noted the bone will likely be quite
porous so it'll be important to not get it too wet and to start in an
inconspicuous area. Take care with the friability of the surface if it's in
poor condition. This may take forever depending on your collection, so some
decisions may need to be made as to how to proceed or other options. If the
water doesn't work you may need to try various solvents. Others may have
suggestions that will be less time consuming or better for use on bones; I
haven't had to deal with large scale glue/adhesive removal on bone and I'm
assuming the mammoth bones are quite large and numerous. There may be a larger
scale way to deal with them.
Good luck!
William Shepherd
Collections Officer
Swift Current Museum
44 Robert Street West
Swift Current, Saskatchewan
S9H 4M9
Phone: 306-778-4815
Fax: 306-778-4818
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