What Makes Clay Pottery Watertight & Fire Resistant?
Pottery has been an important craft for making bowls, vases, jars and other containers since at least Neolithic times. Pottery is useful for containers because it can be made fire resistant and watertight through the processes of glazing and firing.
Other People Are Reading
-
Drying
-
After the potter finishes shaping a vessel, it is dried for several days until it becomes stiff and leathery. If it enters the next step, called firing, without drying, intense heat will boil moisture trapped in the clay and the escaping steam will crack the pot.
Firing
-
After drying, the pot is placed in a special oven called a kiln and baked at intense temperatures in a process called firing. When it is removed from the kiln, the pot is hard and heat resistant but still porous enough to absorb a special paint called glaze.
-
Glazing
-
After applying the glaze, the potter returns the pot to the kiln for a second firing. Glaze contains silica; when heated, the silica and other ingredients in the glaze melt and fuse together, forming a glass-like coating. The coating gives the pottery a pretty color but also makes it impervious to water.
History
-
Making pottery heat and water resistant by firing was likely discovered by accident, when someone left a clay-lined basket too close to a cooking fire. This would have destroyed the basket but left behind pottery.
-
