Matting agent for Acryloid resins

Laura Smalarz <preservationworkslrs [at] msn__com> writes

>...  All of the acryloids/paraloids (B72, B67, B48N, B44)
>produce a glossy finish.  Is there anything I can add to create
>matte and semi-gloss sheens? I know that Liquitex makes Soluvar in
>different sheens that I can apply over the different Acryloids, but
is this my only option?

I have found fumed silica to work very well.  As I understand, it is
also what many commercial coating manufacturers use to vary matte
and gloss in their products.  These silicas are very finely divided
and lightweight powders -while in the jar, they almost behave like a
liquid because they are so fine.  The more you mix into your
coating, the more matte the resin will get after drying.  They also
tend to settle out after sitting for a few weeks, but they can be
easily redispersed by mixing.  I bought some from Conservation
Support Systems a few years ago, and have been very pleased with
them.  They sell both hydrophilic and hydrophobic varieties; for
your work, it sounds like you would probably want to use the
hydrophobic type.  I think some rock climbers and gymnasts also use
these as a kind of talc; apparently they can improve your grip.
Fumed silicas also require some caution to use, as they are very
finely divided, and thus are an inhalation hazard.  I only open the
jars in the fume hood.  I hope this is helpful,

Thomas J. Braun
Daniels Object Conservation Laboratory
Minnesota Historical Society


                                  ***
                  Conservation DistList Instance 17:71
                   Distributed: Friday, May 28, 2004
                       Message Id: cdl-17-71-005
                                  ***