Hardness of bisque based on drying time

Jun 26, 2004 4 Replies

I recently read on the back of a bag of grout that we should be spritzing it with water so that it cures at a slower rate. Does the same stand true for drying clay bodies? If I figure out the fastest way to get a piece of clay to greenware without it cracking or warping, will the bisque eventually be more brittle because it didn't have as long to 'cure'?



Thanks



John



Very different things ... apples / oranges... The grout is going through a chemical change that generates heat and requires water as part of the change in chemical structure. Clay drying to be fired is simply losing water. As it does so the body shrinks and you want this process to be slow enough that you do not create stress points by one part of the body losing water faster than another part (leading to cracks or warping). This is why you use a damp closet to allow pieces to keep uniform amounts of water when you have added a handle or why you wrap in plastic to keep the piece from drying to quickly. Greenware is unfired clay. You want the water out of your clay as much as possible when you fire it (bone dry) so that the H20 going from liquid (water) to gas (steam) does not make the pot explode. There is no 'curing' involved. There is always some water in the clay no matter how long you let it dry. This is why it is so important to bisque fire slowly (heat soak) to the point that the water has completely turned to gas. There are other points that you have to go through slowly as well (when chemical changes occur and the body will be expanding or contracting). The below site is a wonderful place to get information from.

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