Majolica painting problem (cobalt paint recipe please ???)

Nina, you might try the cobalt with just water, or with water and a bit of gerstley borate, I'd have to look up the percentages at the studio. I usually eyeball the cobalt with some water. Cobalt tends to spit like that, but it might be a problem with the clear glaze. Try a few tests. Hope this helps.

Cea

Are you using cobalt carbonate or cobalt oxide? I use just colbalt carbonate mixed with water and have never had a problem with it (hard to see because of the pink color... some vegetable food coloring might work to make it more visible if that is necessary).

From memory when I did majolica it was 50% colourant and 50% frit added with water I can check it out for you. As someone else mentioned though I think what you have to do is lots of testing. Test with cobalt carbonate and oxide, test your coppers and magnesiums and irons etc at the same time alone with commercial stains. Do them with glaze, with just frit, lots of testing because every glaze and every kiln is different and so testing is always the key. Remember also that majolica is not food safe, the colourants are not tied into a glaze and therefore release oxides etc. A