Aluminum foil is wrapped around the pot to contain fumes so that the pot picks up color from the fumes. Firing at various temperatures brings out different colors. Various combinations of ferric chloride, copper sulfate, sugar, salt and horsehair achieves diverse effects. There is no way to predict the outcome of a finished piece. Each one is very unique.
Horse hair is applied by heating up the already once fired piece to 1500 degrees, taking it out of the kiln and applying the horse hair from the tail of the horse to the pot, which leaves a black carbon foot print. The natural color of the clay is white. The red to golden orange values are made by spraying ferric chloride on the hot surface.