Last weekend I went to Burnt Earth Studio in Forest Row to teach a glaze course with potter Candice Coetser. We spent the first day mixing up a base glaze and adding colouring oxides.
At the end of the day we loaded the glaze tests into the kiln. Each student made 15-20 glaze tests with various combinations of five different colouring oxides.
We fired the kiln overnight. The next morning, I gave a talk on glaze chemistry and after a delicious lunch we managed to open the kiln at just below 200 degrees C.
The glaze tests came out really well. Most students were interested in matt glazes. They tried adding cobalt, copper, titanium, nickel, manganese and tin oxides. An interesting discovery was that nickel oxide makes a light apple green in magnesium matt glazes. The favourite colour was the duck egg blue made from a combination of copper and tin oxide. There were also some interesting pinks and mauves from manganese and titanium. I will be back in Forest Row in April teaching at Forest Row School of Ceramics.