Earthenware A low-fire clay. Porous and not waterproof. To be functional, it needs to be glazed. Firing Clay is hardened by heating it to a high temperature, fusing the clay particles. Primitive pottery is usually fired on the ground or in pits with whatever flammable material is available.
Kilns allow a more efficient use of materials and more control over the atmosphere during a firing.
The two basic atmospheres, oxidation and reduction, affect the color of the final piece. Glaze A coating of material applied to ceramics before firing that forms a glass-like surface. Glazes can be colored, opaque, translucent or matte. Kiln The furnace in which ceramics are fired. Kilns can be electric, natural gas, wood, coal, fuel oil or propane.