Refiring pot melt
My question was about the centring of the pot above the circular dam. If not centred, It can leave you with more glass on one side than the other, if the high temperature soak is not long enough to allow a flow to equalisation.
333C/hr seems a bit fast for the ceramic pot, but if it is surviving, fine. The 20′ soak at 538C seems odd and unnecessary. Why you slow down to 140C/hr for 55C after 538C is also a mystery to me. If you want a soak to let the air out from between the glass pieces, this should be done in the region of 650- 677C with a soak of ca. 30mins. In general people speed up as the glass gets warmer. You seem to be slowing and then speeding up, but not to your initial rate of advance of 333C/hr. Odd. I think 838C (1540F) is too hot for your equalisation temperature, try your full fusing temperature instead. I would use the Bullseye schedules for annealing thick pieces and go from your equalisation temperature afap to 482C and then apply the schedules.
You can use either, although in this case I would use batt wash as you want the glass to move and that might pull the thinfire into the glass. I – unlike most people – do not use thick layers of batt wash. I spray the wash onto the shelf until it is uniformly pink. This is not very thick. All you are trying to do is to keep the glass and the shelf separate.
I think you are asking whether to clean the present back, turn it upside down, dam and then fire slowly to 815C. If so yes, but you will need a much longer soak to allow the glass to move and become approximately the same thickness all the way across.
Just as using the imperial system is to me.
So the difference is 3 mm (not the 7 mm you indicated it might be) This means that you could fire as for 15 mm [5/8 inch]. This would mean an initial rate of 90C/hr to 250; 115C/hr to 500; 150C/hr to top temp. [no bubble squeeze required].
This would indicate to me that you have not yet settled on a firing schedule. Are you keeping notes so you can compare the results of different firing schedules on different amounts of glass and of different colour combinations?