Waterlogged leather

Maria Grammatou <mgrammat403 [at] yahoo__com> writes

>We have found a piece of waterlogged leather together with copper
>coins, obviously it must have been a small leather bag. The biggest
>fragment is of the size of a thump and it carries some small coins.
>There is not enough leather to experiment various treatments. Which
>would be the safest procedure somoone could follow so as to preserve
>it? Maybe a PEG would be suitable, but which one would be best? The
>literature is a bit scary always mentioning procedures that fail and
>succeed even for different pieces of the same object. Any help will
>be appreciated.

I can completely understand your feelings on treating waterlogged
leather. Every text will have a different method with different
consequences. I am going to assume that the leather does not have
any pigments that need special attention. The method below is how I
conserve most of my leather. I have objects that were treated with
this method that are still stable after 10 years of being in storage
and display cases so in my opinion it has worked well for me. I do
not use PEG for three reasons: it is costly, some of my colleagues
have reported a few issues with long term storage and even though
PEG is not supposed to corrode copper it has changed the copper
color on me . Of course I know other conservators who have had PEG
impregnated leathers do fine for over 40 years. Again, this is going
to back to every report being different.

I would soak the object in de-ionized, reverse osmosis or at least
distilled water for at least 1 week changing the bath everyday. This
is to leach out any chlorides or other minerals that the bulking
agent will bring to the surface later. This will also break up any
soil concretion which you can lightly clean off. (Assuming it is not
fragile to touch).

After the bath I would soak the object in a 30%glycerin / 70%ethanol
bath for up to 3 weeks. I have never had a problem letting an object
sit for up to 6 months in this solution the longer the better.

After 3 weeks let it dry in a very low humidity/temp room blotting
the glycerin that may come to the surface.

Now you have three options for a final dressing or treatment: Bavon,
Micro-crystalline wax and/or freeze drying

My leathers are always still quite sturdy so I am able rub in the
wax manually. If the object is fragile consider a soak in Bavon or
the British Museum dressing. At this point you could also freeze dry
the object. I have had less than 5% shrinkage with the above method
without freeze drying. If you do not have access to a freeze dryer,
Email me and I can give you a low tech alternative. Alternatives for
ethanol are 90% iso alcohol and acetone. My methods are usually
considered overkill but I would rather be safe than sorry. Hope this
helps,

Wyatt Yeager


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                  Conservation DistList Instance 22:31
                 Distributed: Friday, November 28, 2008
                       Message Id: cdl-22-31-003
                                  ***