I'm not sure that's it, because they didn't really melt, just changed a bit and when ever I do decals on ^10 pieces, I refire to ^06 fine. Is there any way for me to figure out what temp the cups were originally fired to aside from testing until it melts?
I've been doing some tests on commercially made ceramic mugs, to see how I can improve them. I have had the most luck with decals, which I fire to ^06. The only thing is that I have had some go metallic or get really small bubbles on the glaze. I'm not sure why this is. Has anyone else done this? Or could tell me about the commercial ceramics process (especially kiln temperature)? Other input?