Often I feel like I’m in a “test mode” when it comes to glazing ceramics. I used cobalt oxide wash on two different bowls with quite different results, likely due to the the glaze underneath the oxide wash.
On one bowl, I added dots of the blue oxide wash atop a transparent white glaze with a squirt-bottle tool. The transparent white is a standard “studio glaze” – one of several offered to members of the studio where I work, Midwest Clay Project. I wanted the blue oxide to look like blue berries, and indeed it did.
On another bowl, I added the blue oxide wash with the same squirt-bottle tool. This bowl was coated with white slip (thin porcelain clay) pre-bisque, then coated with Amoco Celadon Ice and decorated with the oxide wash and another glaze. Both bowls were fired to cone 6, or 2269 degrees fahrenheit. This time the blue oxide turned purple with a very thin blue outlined edge, due to a reaction with the chemicals in the Celadon Ice. This photo shows the blue oxide in the purple straight lines outlined in blue. The larger blue dots are not the blue oxide, but a studio glaze called “Floating Blue.”
The Celadon ice “crazed” as the pot cooled. Crazing is a network of very fine cracks in the glaze, said to be caused by a mis-match between the clay and glaze. I adore the crazing on this piece. Here’s a close-up shot of the crazing.
This sweet little bowl, approximately 3.5 inches high with a 6 inch top opening, is one of those interesting glaze wonders. Although I wanted the lines to be blue, I’m delighted with the purple! And I love the crazing! I guess this time I got lucky:)