On that kiln you should be
On that kiln you should be able to fire using only the lid.
Three things would help me help you:
- What is the kiln model
- Does the kiln have a controller
- What is you firing schedule
Is there any chance the lid/sides switch is operating the opposite of what you think (maybe it is labeled backwards)? Heating just from the sides can cause the bubble problem you describe.
Helios Kiln Glass Studio