Elke

Thank you thank you everyone!! After more research I do think it was partly a temperature issue, copper needs high temps to burn out and for the glaze to move and run. I alos used my gas Port-o-kiln which is desigend to rapid cool unlike the wood kiln I had used before. This batch of glaze had been tested in a kiln run off gas and also waste vegetable oil (a very experimental sustainable kiln), in oxidation , and it came out perfectly transparent, shiny and green. I definitely did not go into reduction, I have fired this glaze in reduction to cone 10-11 and it goes a marvellous shiny spotty glossy red. The matt metallic black was a surprise. MY QUESTION (for those how know a bit about glaze chemistry and heatwork) Will the metallic black burn off if I refire to cone 12-13 and cool slowly? I am thin on time, so I want to crowd source some advice to make the smartest move. I have attached screengrab of the original wood-fired green pot and my misfires black pitchers. Both were lined with Tenmoku. THANKS!

Hello glaze makers! I have a very niche issue and thought someone here maybe able to help me. I was commissioned to make a series of 8 large bespoke ceramic pitchers in a specific colour. They are to be presented as awards at a commemorative event on Dec 10. My customer selected a soft green finish from one of my existing pieces that was glazed in a traditional oribe glaze and fired in oxidation in a wood kiln ( in a group fire in Gunderoo NSW) I have a small Port-o-Kiln and assumed I could replicate the green colour by using the exact glaze (same original batch) and firing to cone 9-10 in oxidation in gas. When I opened the kiln this morning all were BLACK!! I am not sure why. Its either because I didn't go high enough - I found out the group Gunderoo wood fire went to cone 12-13. Or because it Port-O-Kilns cool quickly and when you look up oribe on Wikipedia there is a section that says Black Oribe is achieved with a rapid cool down. Either way I have to urgently refire existing pieces to cone 12-13 or remake all agin which is a ton of work. Does anyone have any understanding of the chemistry behind this? Could I refire to higher temp and the glaze continue to mature and achieve the green colour? Any advice or insight is greatly appreciated. RECIPE Potash Feldspar 60 Wood Ash 20 Whiting 10 Ball clay (clay ceram ) 10 Bentonite 1 or 2% Copper carb 7.5