I never had this happened before so I am perplexed. I was following a program for fiber paper as a texture base for my glass.
12″ glass circle-System 96 3mm clear over 3 mm transparent blue over fiber paper. 3 mm Center 5″ circle opal blue. Large hole in opal blue, large spaces under opal blue. Small uniformly place holes along the edge of the piece on top facing. I want to include photos but I can’t upload them- help here to. I have them on my desktop. Firing schedule in a 24 x 24 Jen Ken kiln top & side elements. Did the fiber paper hinder the even heating where there was 3 layers of glass? But why did the edge have uniformly spaced holes on the surface?