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terra sigs

updated thu 31 jul 97


Linda Arbuckle on sun 16 mar 97

John Jensen asked about burnishing sigs. I'll throw in my 2 cents.

Burnishing a pot and buffing a sig are two different things, although at
some points they look similar . Burnishing compresses the surface and is
done with a hard object... stone, back of a spoon, etc., and usually done
before the pot is totally dry. I don't have a great deal of experience with
burnishing, but info I've seen here and elsewhere indicates that firing
above low lowfire temperatures results in enough movement in heating,
melting, cooling of the clay surface to destroy the alignment that made the
nice, buttery surface sheen.

Sigs are very tiny particles of clay. Most people apply to bone dry clay
(dip, brush, spray). Too thin a sig, or too thin an application, and you
don't get much sheen. Too thick and the tiny particles may hold on to each
other better than the clay body, and peel off after firing. If you use a
good sig and get an appropriate amount on (usually for me the sig is at milk
consistancy, and I dip or brush pot bottoms on lowfire ware to a count of
15. For a whole piece, you wouldn't want to do it this way for fear of too
much water absorbtion and cracking), you can buff it up with your fingers or
a soft cloth. I've used ritz hotel shoeshine cloths, handiwipes or pellon
interfacing from the fabric store (both are soft poly without grain), blue
automotive shop wipes, and students at UF are now using soft foam cosmetic
sponges. So, the idea is to buff the sig, not compress the surface. The
shine on sig is durable over a wider temperature range.

Pete Pinnell has done some really lovely work at 03 working with sigs fired
on in the bisque-firing, and then he applies a "patina" of flux and
colorant, put on and wiped off like antiqueing. Really nice on textured
surfaces, and modifies the flattness of the sig surface. He uses 1 teaspoon
gerstley borate to 1/2 teasp. (strong colorants) to 1 teasp. colorant. Test
various colors of "patina" over various colored sigs. A tin patina over a
chrome sig does give chrome-tin pinking.

Linda Arbuckle
Graduate Advisor, Assoc. Prof.
University of FL Department of Art
P.O. Box 115801
Gainesville, FL 32611-5801

Leslie Ihde on wed 30 jul 97

Linda- I saved your message on terra sigs- which I found very informative.
I wanted to know if terra sig can be applied to bisqued paperclay? Do you
know of a book which addresses the application of terra sig to bisque? I
wonder because you said useally terra sig is applied to greenware. Are
there other ways?
Thank you for any leads for further reasearch. (Meanwhile, I will
experiement of course, but suggestions are appreciated.)
Leslie in Vestal NY