Saturday, March 14, 2009

Coming to terms with clay.

I was wondering how many folks are familiar with some of the basic terminology
used in a mud shop? (other than mudders of course:)
After listing a couple of "slip-cast, bisque ware" pieces on my Etsy store...

I realized that I was using clay-speak which may not be well understood by everyone.
So I thought it might be a good subject for my blog.

First of all there's numerous names and types of "clay". I've divided them into two categories:

Manmade- polymer clay, fimo, resin, plaster, paper mache, playdough are some examples
of what are often called "clay".
There are so many types of manmade clays. They are great for the novice AND the pro.
The best part is that no special equipment (kiln) is required, so it is accessible to everyone!
Although they can be pricey- the size of your creation will have a big effect on the cost of your materials.
-some come in a block, in assorted colors,
- others are powders that you mix with water.
- you make your item, then let it air dry.
- Some types will harden and be finished,
- others just need to be painted at this point.
- Then (for some types) you must bake it in a (regular household) oven,
(to maintain the permanent shape,) and may or may not need to be
painted or sealed.

Natural clays-
Earthenware, stoneware, porcelain, bone china, Hi-fire, Low-fire, terra-cotta are some examples of natural clays. Most are processed to remove impurities, and to alter the plasticity of the clay.
Here's a link for more great info about natural clay:

These clays are all very breakable in the greenware stage, and must be fired to maturity to make them strong and permanent.
Earthware- low-fire opaque clay
Stoneware- Medium to High-fire opaque clay
Porcelain- High fire clay (often somewhat translucent.)

Terms often used for natural clays:

Bisque: Clay that's been fired once, often to maturity. It is strong and ready to be
displayed, but more often is painted (or stained), or can be glazed and then fired again.

Cones: Used to determine maturity of clay as it's being fired. (kind of technical, I'll add a link
here soon)

Firing: Heating clay to maturity, where it is no longer porous. Usually fired in a kiln.
Mudder's don't usually use temperature to describe how it's been fired, we use "cones".

Greenware: Clay that's been shaped into a form and dried.
It is very fragile at this stage. If an item is broken at this stage, it can sometimes
be fixed or more often, pulverized, water added, and re-used.

Leather stage: When clay is partially dry, it is great for carving details and holds it's shape, but is
very breakable.

Mudder: A person that works with clay.

Slip: Liquid clay used to pour into a mould, (also great for fixing broken greenware.)

Slip cast: A piece that was made by pouring slip into a mould, allowing some of the moisture
to be absorbed by the mould, removing piece from mould, allowing it to dry.

Whiteware: Is usually a plaster piece ready for painting, sometimes used "incorrectly" to
describe bisque ware.

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