I just completed my first glaze load. There were several things that I need some help with - and would love to hear your insight. It was a slow ramp to Cone 6 with a 4 minute hold.
1 - Several pieces cracked.
Three plates, a bowl, and a cup. Why might this happen? How can I avoid this happening in the future?
2 - Some of my glazes did not turn out correctly - at ALL
One was Spectrum Crimson, the other a home made turquoise. The commercial crimson turned out glossy white - with the occasional purple-ish streak. The turquoise turned out a matte white, with an almost chalky quality. The glazes were well mixed and sieved; I'm wondering - is it possible for colour to burn out? For example, the commercial glaze says it's good for Cone 4-6, and I fired to Cone 6. Could this particular glaze possibly need to be fired to Cone 5 only? Other ideas?
3 - Bubbling
A few pieces came out with bubbly glaze - very badly on one piece in particular. It wasn't the same glaze (one was cobalt blue, the other a glossy black). I was told that soaking the load for longer would help avoid this... I also heard that one shouldn't soak too long, as it can cause over firing. What do you think - and how can this be avoided?
4 - Guide Cones
The cone 5 guide cone was completed melted, not just bent over/slumped. The cone 6 guide cone hardly had a wobble in it. Why would cone 5 look SO over-done, while it looks like cone 6 was barely reached?
Thank you so much! I was pretty bummed when I opened the kiln... however, I still consider it a success as I am learning so much. There were several interesting pieces, nothing exploded, nothing stuck to the kiln shelf... (I like to look on the bright side).
Thanks again for your insight!