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.

A caution about using dyes to monitor gel residue--the dye may
associate closely with the polymer molecules of the gel, but may
also be carried by the solvent away from the gel and deposited, so
that you have an "apparent" residue that is only dye; conversely,
the dye might be carried up into the bulk of the dried gel that is
removed, and not stay with the residue, giving you less visualized
gel residue than you really have.  (Mixtures generally do not stay
perfectly mixed when in contact with a separating medium, such as a
porous object, especially when solvent evaporation is involved.)  I
would tend to think you are more likely to get falsely high
readings, as the dye molecule is smaller than the carbopol and more
likely to get trapped in pores.

I don't have a solid suggestion, but recommend you focus on making
the residue visible after "treatment" by experimenting with stains
that react with the carbopol.

Mary T. Baker
+20 2 380 5807 (Egypt) direct phone
Mailing Address:
Chemonics International, Egypt/MVE
1133 20th Street, NW, Suite 600
Washington, DC  20036
Shipping Address:
49, Road 81, Apartment #1
Maadi, Cairo  Egypt


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                  Conservation DistList Instance 14:31
               Distributed: Wednesday, November 29, 2000
                       Message Id: cdl-14-31-001
                                  ***