To fast on heat up

[Stephen Richard]

The temperature you witness the break at shows you are firing too fast.  The steel drains the heat from the centre of the glass, but the suspended glass heats up more quickly, leading to sufficient stress to cause breakage.  Slow down.  Depends on the thickness as to how much you need to slow the temperature rise.  Paul will have some schedules here in the tools section to help.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/ and  http://www.glasstips.blogspot.com/