I mixed cobalt and amber purple in a new way and it turned muddy brown

I was working on a vase last week and decided to layer a thin gather of cobalt blue over a thick base of amber purple, thinking it would give a deep violet shift. I heated it to about 2200 degrees and worked it for maybe 15 minutes. Instead of a rich color, the whole piece came out a flat, dull brown, like old coffee. I learned that those two colors just don't play nice together at high heat for long periods. Anyone have a good combo for a deep violet that won't turn to mud?

2 comments

2 Comments

casey_torres601d agoMost Upvoted

That's a classic browning reaction with those colors. I read an old forum post about how the manganese in amber purple and the cobalt can just cancel each other out and turn brown if you cook them too long. For a deep violet, I've had good luck using a light amethyst as a base with just a tiny hint of cobalt on top. You have to work it hot and fast, get it shaped, then stop. Keeping the heat time way down is key.

sanchez.mary1d ago

Wait, the manganese and cobalt can actually cancel each other out? That explains so much. I ruined a whole batch last month trying to mix those exact colors and just got muddy brown glass. @casey_torres60, your tip about using amethyst as a base makes total sense now. I always thought I was just overheating it, not causing a chemical reaction. So you really have to get in and get out fast with the heat, huh? I'm going to try your method this weekend.