Vocabulous
Feb. 4th, 2015 05:22 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
offcntrBeen awhile since I talked terms…
Greenware. Green as in fresh, new, not as in color. This is just unfired pottery, generally used when the work is dry, e.g. "I just loaded a batch of greenware into the kiln." Oddly enough, the painted ceramics world uses it to describe bisqued ware. I had to explain this one a zillion times, back when I was teaching.
#1 Pottery Plaster. The best quality, most uniform plaster for making molds. Better than Molding Plaster and much better than Plaster of Paris.
Cottle. The walls of a mold into which you'll pour plaster. For a small mold, you can use a thick slab of clay, well stuck to the base board. Larger forms will be contained by boards, clamped together at the corners, well-sealed with clay or plasticene coils at the base and seams, and liberally coated with a mold release.
Mold release. A substance that keeps plaster from sticking to the piece being molded, the bottom of the mold or the cottles. Typically Murphy's Oil Soap, or an aerosol mold spray. For quick-and-dirty projects, WD-40 or kitchen pan spray will work. If you're making a single mold from a wet-clay original with clay slab cottles, don't bother with any of this stuff. Just peel the clay out when the plaster is set.
Slip mold, press mold. Different ways of using plaster molds. A slip mold is poured full of specially formulated, deflocculated (don't ask. I'll explain some other day) liquid clay slip. After a set period of time, during which the plaster absorbs water through the inner surface of the mold, the excess is poured out and the remaining shell of clay is allowed to harden before it's removed from the mold.
Press molds require less chemistry. Plastic clay is pressed into the mold with fingers, a sand-bag, sometimes a rubber mallet. Excess clay is trimmed away, and the piece is allowed to set until the surface has been dried by the plaster until it is no longer sticky, then removed.
Sprig. A low-relief decorative element on a pot. Usually made with a small press mold. The mold is pressed full, extra clay is removed with a wire, and the mold is positioned over a scored/slipped spot on the pot. Moderate pressure attaches the sprig, at which point the mold is removed and filled for the next sprig.
Greenware. Green as in fresh, new, not as in color. This is just unfired pottery, generally used when the work is dry, e.g. "I just loaded a batch of greenware into the kiln." Oddly enough, the painted ceramics world uses it to describe bisqued ware. I had to explain this one a zillion times, back when I was teaching.
#1 Pottery Plaster. The best quality, most uniform plaster for making molds. Better than Molding Plaster and much better than Plaster of Paris.
Cottle. The walls of a mold into which you'll pour plaster. For a small mold, you can use a thick slab of clay, well stuck to the base board. Larger forms will be contained by boards, clamped together at the corners, well-sealed with clay or plasticene coils at the base and seams, and liberally coated with a mold release.
Mold release. A substance that keeps plaster from sticking to the piece being molded, the bottom of the mold or the cottles. Typically Murphy's Oil Soap, or an aerosol mold spray. For quick-and-dirty projects, WD-40 or kitchen pan spray will work. If you're making a single mold from a wet-clay original with clay slab cottles, don't bother with any of this stuff. Just peel the clay out when the plaster is set.
Slip mold, press mold. Different ways of using plaster molds. A slip mold is poured full of specially formulated, deflocculated (don't ask. I'll explain some other day) liquid clay slip. After a set period of time, during which the plaster absorbs water through the inner surface of the mold, the excess is poured out and the remaining shell of clay is allowed to harden before it's removed from the mold.
Press molds require less chemistry. Plastic clay is pressed into the mold with fingers, a sand-bag, sometimes a rubber mallet. Excess clay is trimmed away, and the piece is allowed to set until the surface has been dried by the plaster until it is no longer sticky, then removed.
Sprig. A low-relief decorative element on a pot. Usually made with a small press mold. The mold is pressed full, extra clay is removed with a wire, and the mold is positioned over a scored/slipped spot on the pot. Moderate pressure attaches the sprig, at which point the mold is removed and filled for the next sprig.