From:    "Michael A. Lewis" <[log in to unmask]>
Subject: Tortoise-shell comb
Judging from your description of the damage as it is progressing, I'd
guess that this comb may be a celluloid example, and not tortoise shell
at all.  This material, a cellulose nitrate and camphor plastic that
dates from 1868, was widely used to imitate tortoise and occurs
frequently with toilet articles.  It is a flammable and light sensitive
plastic that deteriorates in somewhat unpredictable ways including the
cracking and crumbling you describe.  If metal objects are in close
proximity they may be corroded by the off-gassing deterioration products.
  Isolate the comb, keep it cool, and get it to an objects conservator or
a conservation scientist in your area to test the material for
identification.  Any advice about long term stabilization will need to be
based on an accurate identification of the material.

Kory Berrett
Objects Conservator
Fellow, AIC
3054 Reisler Road, Oxford, PA   19363
(610) 932-2425

You wrote:

        I have an intertersting conservatioing conservation problem.
        I have recently encountered a tortoise-shell comb that is
deteriorating from the edge of the handle, pndle, progressively over
thpast five years. The material is craking in a geometric pattern and
crumbling int a powder. The damage is progressing from one corner along
the edge of the handle of the comb.
        The comb has been kept in a plastic zip-lock bag in a drawer
during the period of deterioration, in a private home that has been at
room temperature but in uncontrolled relative humidity.
        I would appreciate any suggestions on how to stabilize this piece
and at least stop further deterioration.
        Thanks!
        Michael A Lewis
        University of Alaska Museum

_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]