I’ve been teaching the microwave kilns for a few months here. Here’s my latest thoughts –
The new microwaves are nice, but they seem to be more powerful than the last one. I’ve started doing 5 minutes at 50% power, because I was getting cracking glass, regardless of the size of the fused piece.
So, while in general the bigger the piece, the more time it needs for a fuse, that extra time seems to be pretty small.
5 min 50%, and 6 minutes full power – fully fused, and tending every so slighter toward blob.
At 5 min 50% and 4 minutes full – not beginning to fuse. Plus 1m30s fully fused.
5 min 50% and 4 m 30 sec full – red hot but edges still looked sharp. Added 30 sec – not fully fused, but no sharp edges.
Still had one of the bigger, piled high pieces crack even with the 5 m at 50%. Might go to 6 m 50% for large and multi-layered pieces.