@nprofile1q... @nprofile1q... @nprofile1q... I'm using the regular Bungard boards from Reichelt. I can never tell if that's called positive or negative. Exposed areas disappear.

For now, I'm warming it by pouring hot water to the bowl once or twice per board, and I'm agitating manually with the pictured tool. The good part is that I know immediately when it's done :P

But yeah, I'll have to find an aquarium heater.