eoteceramics Posted May 21, 2022 Report Share Posted May 21, 2022 Hi everyone from Sunny Ireland! Im hoping someone can help before I ruin another load of work! Pot on the left is what I am trying to achieve, it was a happy accident as I just wanted to fill a space. I think I put a thinish layer of Copper Carbonate on then a layer of transparent glaze and fired to cone 05. Delighted with the colour I tried to repeat it, Pot in the middle has a thick layer of the same , my thinking was it would be even more blue, it wasnt!! The next item was treated the same and the transparent glaze seems to have crazed and cracked and is a nasty colour , the final item had no transparent glaze on it , again black/brown colour. How can they be so different? Was it because I put a thick layer on and why would the transparent glaze react that way? I know there will be someone in this community who can help, Thanks So much, Jools Quote Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted May 21, 2022 Report Share Posted May 21, 2022 Short answer is yes, it’s the thickness of your copper carbonate layer. Rather than giving more blue, it’ll go metallic, like you see here. Too much, and it can make the glaze over top craze like in the third pot from the left. The metal is just overpowering the glaze, and it doesn’t take a lot to do that. All glazes rely on the proper proportions of the different ingredients to turn out the way you want them to. Copper by itself, or in enough quantity to overpower the other glaze ingredients, will turn a metallic black like the pot on the right. When you mix sodium (a pretty common glaze flux) and a little bit of copper, it gets that signature turquoise colour you’ve got on the first pot. If your goal was to eliminate the dark streaks like the piece on the left, you would have wanted to add slightly more glaze, where the sodium is coming from. Or, if you wanted to get a bit more scientific about it, you could add a little copper (1% or less by weight is usually enough) to your glaze base to make a turquoise. This is done most easily if you’re buying a dry mix, because you just weigh dry ingredients out. But there are ways of getting repeatable results if you have to add dry carbonate to an already fluid glaze. shawnhar, Hulk and eoteceramics 3 Quote Link to comment Share on other sites More sharing options...
eoteceramics Posted May 22, 2022 Author Report Share Posted May 22, 2022 Thanks Callie for explaining all that in such detail/ It was my hunch that it was too thick but so glad you have confirmed that and I can get back to work. Have a great day, Jools Callie Beller Diesel and Hulk 2 Quote Link to comment Share on other sites More sharing options...
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