Complicated firing schedule

[Stephen Richard]

In my view you have a complicated firing schedule.  A good way of testing your schedule before committing youself to it is to be able to explain the purpose of each step of the schedule.  For a fuse firing fo 6 mm thick for me, go at a single rate to the bubble squeeze, soak there for 30 mins and then advance at a quicker rate to the top temperature (trying to get the work done in 10 mins).

The reasons for this – a steady initial heat rise to ensure the glass is all increasing in temp together. the bubble squeeze is to allow as much air out as possible at or near the slump temperature for that glass.  The more rapid rise to top temperature is to get through the devitrification range as quickly as possible. [I’ve left out the cool and annealing portions].

A review of the S96 web site will give you information on both the bubble squeeze and temperatures for various processes.

Small, pin head sized bubbles are a feature of kiln formed glass, as they are already in the glass, unlike blown glass.  Re firing will not get rid of these bubbles, unless you wanted to go to a high temperature for a long time.  And then you would probably ruin the piece.

Stephen Richard

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