SUDDENLY ...air bubbles..SUGGESTIONS PLEASE?

[JoanG]

I've been full fusing 7 inch plates for years, using the same schedule. I use a small hot start kiln that doesn't allow much in terms of controlling the heat, ramp speed, etc. I use a tiny amount of glue to hold the top and bottom pieces in place. Suddenly there are "bubbles" under the top layer and the glass isn't firing flat for the full fuse. I'm not sure how to attach a photo but any ideas or suggestions would be GREATLY appreciated! Thank you.

[Jordan Kube]

Perhaps you've lost an element or they are getting old, etc.

[Brad Walker]

What schedule did you use? Is the top or bottom glass a different one that the one you've used in the past?

Does the kiln have top only elements or side and top?

[Emily Speight]

is there any possibility that your shelf has a small dip in it? perhaps you were using one side and flipped it?

while it's a workaround, a very fine sifting of clear powder between the layers can help prevent bubbles.

i would like to see your schedule...