Sunday, February 5, 2012

It's Silly Sunday of Clay Week!

Welcome to a week of clay posts while I'm working on lampwork. Makes sense, right? Actually I made the posts while I was working on clay last week so I could show you all the new things I've learned while I work on lampwork to go with the new clay pieces.

I thought I'd start this dialogue with definitions of what each process is. That way if something I'm posting doesn't make sense you can always go back to the list. Like every medium ceramic clay has it's own "lingo". Feel free to copy the list - there's more but I tried to shorten it to cover what I might talk about.

It is "Silly Sunday" so enjoy the joke. Forget the list until next week when it sounds like I'm talking through my fanny trying to explain a technique. I'll try not to be complicated. Have a great and happy day!

BISQUE - Unglazed clay, fired once at a low temperature.
BISQUE FIRING - The process of firing unglazed clay to a low temperature to harden the clay and drive the physical water from it. The approximate temperature of this firing is 1815 F.
BONE DRY - Refers to clay which is ready to be fired. All the moisture is gone from the clay. Clay is VERY FRAGILE at this stage.
CERAMICS - The art of making things of clay. Clay is an ancient tradition.
CLAY – A decomposed granite-type rock. To be classified as clay the decomposed rock must have fine particles so that it will be plastic (see definition below). Clays contain impurities which affect color and firing temperatures.
FIRE - To bake in a kiln. Firing is a term used for “cooking” the clay.
FORM - Three-dimensional shape and structure of an object.
GLAZE - A glassy coating that has been melted onto a ceramic surface. It is used to decorate the piece and to seal the clay surfaces.
GLAZE FIRE - Much hotter than a bisque fire. Firing to temperature at which glaze melts to form a glass like surface. GLAZE FIRING - Typically the second firing of a piece pottery which has been coated with glass forming materials. The approximate temperature of this firing 2300.
GLOSS - A shiny surface.
GREENWARE - Unfired pottery that is bone-dry, a state in which clay forms are the most fragile.
HANDBUILDING - One of the oldest craft techniques in which objects are constructed entirely by hand.
INCISING - Indenting a line into a flat surface.
KILN - Enclosed containers of various sizes- built of refractory brick and heated by electricity, gas, oil, or wood to temperatures from 1500 F. to 2340 F. in which ceramic ware is fired. Also called the “oven” for firing the clay.
LEATHER HARD - Refers to clay that is dry enough but still damp enough to be joined to other pieces or carved without distortion. Clay at this state resembles leather. Hard to bend and soft enough to be carved.
MATTE - Not shiny.
PLASTICITY - Quality of clay that allows it to be manipulated and still maintain its shape without cracking or sagging.
PRESS MOLD - A form which clay is compressed into, resulting in a repeatable shape or texture. These are usually made of plaster. We used plastic bowls lined with cheesecloth as press molds.
SCORING – Roughing up of the surface of clay for joining.
SLAB - Clay which has been made flat by rolling.
SLAB CONSTRUCTION - Handbuilding technique in which flat pieces of clay are joined (clay is flattened and thinned with rolling pin or slab roller)
SLIP – A liquid form of clay used as a glue or as decoration.
SLUMP MOLD - A form which is used to support wet clay in the early stages of construction. They are typically made of plaster. We used canvas covered Styrofoam shapes as slump molds.
STONEWARE – A type of clay which is usually grey in color. It is good for handbuilding and throwing because of its high plasticity.
UNDERGLAZE - Colored decoration applied to bisqued clay, then coated with a clear glaze. Typically made of clay slip and raw pigment

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