Permanent markers

Phillip Seitz writes:
>On the advice of the Smithsonian (which does everything right as we all
>know) we use a layer of soluvar acrylic varnish on the artifact...

I think it important to note that Soluvar is a commercial product (and
we know what *that* means, don't we, boys and girls)!  It was analysed
by Scott Williams at CCI in 1978 and found to be based on poly (n-butyl
methacrylate). Williams analysed Soluvar again in 1988 and found that it
had changed to poly (iso-butyl methacrylate).   Bob Feller (1975) has
described both resins as Class B materials, with photoaging times of
20-100 years, and prone to cross-linking, although he admitted that he
had not seen a sample of Soluvar cross-link.  The matting agent in the
matte version (which might give better "tooth" for writing on) had also
changed from silica to aluminum stearate. (Williams, in CCI Varnish
Workshop Handbook, 1994.)

Why not use Rohm and Haas Acryloid B72 (ethyl methacrylate/methyl
acrylate), which is considered the most stable of the resins we know,
instead of a proprietary product?  It is just as easy to use, although
it takes a little care to prepare.  If you are feeling adventurous and
pressed for time, Williams reports that Lascaux-Fix (available from art
stores) "contains a pure ethyl methacrylate/methyl acrylate copolymer
resin like Acryloid B-72."

The Varnish Workshop Handbook can be ordered from the Canadian
Conservation Institute, and is an excellent successor to Feller Stolow
Jones "On Picture Varnishes and their Solvents".

Lisa Mibach

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                  Conservation DistList Instance 8:33
                Distributed: Thursday, November 3, 1994
                        Message Id: cdl-8-33-002
                                  ***