RE: paleonet Butvar-76 vs. Acryloid-B72

["Judith Harris" <harrisj@xxxxxxx>]

What I really meant by shelf-life was not how long it lasts in its container
but how long it lasts on the fossil. We don't want our fossils falling apart
in a year, ten years, or even longer. As the acetone dries the glue becomes
brittle and breaks.

Judith Harris
Professor Emerita
University of Colorado Museum
P.O. Box 278
Chama, NM  87520
505-756-1813

-----Original Message-----
From: paleonet-owner@nhm.ac.uk [mailto:paleonet-owner@nhm.ac.uk]On
Behalf Of John VanRegenmorter
Sent: Thursday, January 16, 2003 12:13 AM
To: paleonet@nhm.ac.uk
Subject: RE: paleonet Butvar-76 vs. Acryloid-B72



      In the bead form, If stored in a dry place away from light, I believe
the shelf life is very long indeed. Polyvinyl acetate is a plastic. Once
dissolved in acetone it would depend on how long it takes the acetone to
evaporate. Weeks most likely.  What you will notice over a period of time is
the mixture getting thicker and thicker until all the acetone is gone, and
the PVA sets.  I have heard that the PVA is prefered over Butvar because it
last longer on the specimen without discoloring. I have heard over 100
years, but I can't back that up.
JOHN Van Regenmorter

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