Cindy on fri 27 mar 98
Diane,
Whether or not you get pigment from the pastels depends on two things; the
coloring agent in the pastel (is it organic or mineral?), and the
temperature of your firing (is it high enough to burn off mineral oxide
colorants in the pastels?).
You can make pastels or crayons by mixing:
White-firing ball clay 50
Potash feldspar 25
Flint 25
Add:
Bentonite 3
Colorant 15 (maximum)
For a non-resisting pencil, mix with about 45% water to which 1cc of sodium
silicate per 100g of dry material has been added. Dry the colored slip to a
plastic state and roll into "pencil leads" for use in claw-grip drafting
pencils. These should be fired to 800-950 degrees C.
For non-resisting pastels, form into fatter coils or extrusions. You may or
may not wish to fire these to 600-800 degrees C.
For watercolors, form into cakes. Do not fire. Use like ordinary children's
watercolors.
To make crayons which will have a slight resisting effect (particularly
when used on bisque), mix with commercial wax resist instead of
water/sodium silicate. Form crayons and allow them to dry.
I haven't done this, BTW, but it sounds like fun, doesn't it? I think I may
try it today. This information is from Robin Hopper's "The Ceramic
Spectrum" (pp. 133-4) which, IMO, every pottery should own. I bought mine
from the Potter's Shop, but I don't have their e-mail address. (And no,
I don't get a commission. It's just an excellent book.)
Cindy Strnad
Earthen Vessels
Custer, SD
USA http://blackhills-info.com/a/cindys/menu.htm
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