Fluorochromes in solvent gels

Sophie Haake <sophie.haake [at] iname__com> writes

>For a paper that I write at the University of Applied Art and
>Science in Hildesheim, I am testing the effect of solvent gels on
>stone. I would like to mix a fluorochrome into my solvent gel to
>visualize under ultraviolet light the amount of gel residue left in
>the pores of the stone.

This information may be useful for the student interested in general
information on solvent gels as well as relevant for identifying why
there may be problems gelling a Carbopol and Calcofluor mixture.  My
understanding, from playing with various gel agents, is that the
specific directions of a recipe are very important.  Variations in
the proportion, order and timing in which the ingredients are mixed
can affect the gel.

I had trouble trying to add acetone to a Laponite gel and the
technical support staff at Southern Clay Products were able to
provide a great deal of helpful information.  They said that I could
not entirely replace the water with solvent.  Generally the
proportions had to be around 2 parts water to 1 part solvent.  The
Laponite should first be added to the water and allowed to sit for
20 minutes.  At this point the acetone (or alternative solvent) may
be added.  A magnetic stirrer should be used until the mixture
becomes too thick.  If the solvent is added before 20 minutes have
passed the Laponite will not have properly hydrated.  If much more
than 20 minutes passes and the gel has fully formed it will not
accept the solvent--the gel will form with the solvent sitting on
top.  The mixture should be made up weight/weight rather than
weight/volume.

Following these directions did produce a successfully mixed gel
using 36 g Acetone, 60 g Deionized Water, 4 g Laponite RD.  Maybe
the manufacturers of Carbopol will be able to provide similar
information for their product.

Rachael Perkins Arenstein
Assistant Conservator
Department of Conservation
Peabody Museum of Archaeology and Ethnology, Harvard University
11 Divinity Avenue
Cambridge, MA  02138
617-495-2487
Fax: 617-495-7535


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                  Conservation DistList Instance 14:31
               Distributed: Wednesday, November 29, 2000
                       Message Id: cdl-14-31-002
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