Glass and heat
I have no idea what COE in the first message of this thread might be. Normally it refers to coefficient of expansion, and doesn’t tell as much as people think it does. Name the glass and people will know what is being talked about.
Anyway, 703C is not enough to fuse even small pieces unless you soak for a long time. The best thing to do is to look at the Bullseye site tech note #4 under education:
This will help you chose a sensible programme as you will have an idea of what is happening at the various temperatures.
One very simple schedule Bullseye uses for up to 12″ x 1/4″ is:
220C to 677C, 30min soak
330C to 805C, 10min soak
afap to 516C, 30mins
80C/hr to 370