Faience (French) is the general English term for ceramic pieces made with a white buff clay covered in a white glaze suitable for painted decoration. The addition of tin oxide to lead glaze was a huge leap in ceramic technologies in the 9th Century, as it required a kiln capable of maintaining temperatures of 1,000 degrees C (1,830F).
Why would a glass artist be interested in ceramic technologies? The term “faience” also encompasses the glazed beads and objects found in Egypt, Indus Valley, and Europe from as early as 4,000 BCE. These objects are not ceramic, as they generally do not have a clay body but are made from a mixture of silica and salts. Egyptian faience is generally considered to be the parent technology to modern glass technologies. But, more on the history of faience in coming posts…
This is the first test batch of Egyptian faience using the same (modern) recipe for four samples, two using copper (turquoise) and two using chrome (green), of a 1% and 3% saturation of the colourant to test both the colour and the firing schedule. From this initial batch, I have concluded that my further testing will be done with a 3% saturation of copper. While the chrome created a gorgeous green, it remained a matt surface and did not create the gloss of a surface glaze.
Next test batch will be of four different recipes using a 3% saturation of copper fired to 1700 degrees F, after three days, one week, and two weeks of drying to determine the length of time required to properly allow the salts to bring the glass and colourants to the surface.