Table of Contents
Clay is normally fired twice. After the first firing, the clay is called ‘ceramic’. The first firing is called the bisque fire, and the clay becomes bisqueware. The second fire is the glaze fire, and this clay is called glazeware.
What are the stages of clay in order?
What are the 5 stages of clay in order?
- slip. a mixture of clay and water, the consistency of pudding.
- wet/plastic clay. new clay from the bag, very workable.
- leather hard. the clay has lost most moisture, but you can still carve into it.
- bone dry or greenware.
- bisque.
What do we call clay that is ready to be fired for the first time?
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.
What causes clay to explode in the kiln?
The main reason that pottery explodes in the kiln is residual moisture left in the clay body even when it appears bone dry. Once the kiln reaches 212F, the moisture starts to turn into steam. It expands very rapidly and the pottery shatters to accommodate the steam.
What are the six stages of clay?
What are the clay stages?
- slip. a mixture of clay and water, the consistency of pudding.
- wet/plastic clay. new clay from the bag, very workable.
- leather hard. the clay has lost most moisture, but you can still carve into it.
- bone dry or greenware. totally dry clay, all moisture is gone, ready to fire.
- bisque.
What are the 4 stages of clay?
Terms in this set (5)
- slip. a mixture of clay and water, the consistency of pudding.
- wet/plastic clay. new clay from the bag, very workable.
- leather hard. the clay has lost most moisture, but you can still carve into it.
- bone dry or greenware. totally dry clay, all moisture is gone, ready to fire.
- bisque.
Does Clay shrink when fired?
Clay shrinks both in drying and in firing. Different clay bodies shrink at different rates which can be as little as 4%, or as much as 15% for some clay bodies. We also found through out after years of firing that even with the same clay body, shrinkage can vary 1-2% from batch to batch.
Why does clay smell bad?
Why does my clay smell bad? It can get stinky if it becomes polluted with organic material like dead skin from your hands or paper (such as paperclay which has paper pulp mixed in it). Clay can get moldy, in which case you might find it a little unpleasant to work with.
How can you tell if clay is dry?
Clay is bone dry when it has lost all the moisture that it possibly can before being fired. It is dry to touch, and whilst solid, it is very fragile. A common rule of thumb is that bone dry clay feels room temperature when held to your cheek.
Does Clay go bad?
Does clay go bad? No, but it may grow mold. This is good bacteria and will be good for the clay’s workability.
How long can clay sit before firing?
It is generally said that clay can take up to 7 days to become bone dry. When clay is bone dry, it is pale and feels warm and dry to the touch. To prevent your ware from exploding in the kiln, it needs to be bone dry before it is fired. Some potters will put clay in the kiln when it is a bit damp.
What is used to reduce clay shrinkage?
Grog is clay which has been fired then ground up. Grog can come in many particle sizes, from fine to coarse. It is used to reduce shrinkage in clay bodies. The best size of grog for most purposes is a 30/80 mesh.
Is mold in clay dangerous?
It’s true; people can have mold reactions to clay that has mold in it. We’ve heard about several potters that have had allergic reactions to mold in clay. Usually for it to kick up, though, there has to be visible mold—such as you get when a bag of moist clay has been hanging around for a fair amount of time.
Does bisque need to be fired?
Bisque can be painted with ceramic glazes or underglazes and then fired, after which it is water safe. Depending on the glaze, it may be food safe. You need to glaze bisque to use it in those ways. If a luster is placed, it is not food safe.
What does vinegar do to Clay?
Vinegar is also used in clay bodies to increase acidity to improve plasticity. The acid works to neutralize sodium ions (from water, leaching feldspars) that tend to deflocculate the clay. Excessive acid may tend to dissolve more feldspar or nepheline syenite negating the effect.
What is the common name for fired clay wares?
What is the common name for fired clay wares? Explanation: Pottery is defined as the generic name for all fired clay ware, where clay is referred to as a ceramic.
What happens if you fire wet clay?
As it is heated in the kiln, the remaining water will turn to steam as it evaporates from the clay. If it is heated too fast, it may turn to steam while still trapped in the clay and cause the pot to explode!
What is the term given to clay before a bisque firing?
Greenware is the term given to clay objects when they have been shaped but have not yet been bisque fired, which converts them from clay to ceramic. Greenware is unfired pottery. At this stage, it is still possible to work the object by adding more clay, or wetting it so it softens and then reshaping it.
Why do we bisque fire your clay?
The goal of bisque firing is to convert greenware to a durable, semi-vitrified porous stage where it can be safely handled during the glazing and decorating process. It also burns out carbonaceous materials (organic materials in the clay, paper, etc.).
What is fired shrinkage?
Fired shrinkage (shrinkage from dry to fired) is a thus comparative indicator of the degree of vitrification. As a clay is fired higher it shrinks more and more to a point of maximum shrinkage (after which swelling occurs as a precursor to melting).
