I tried again with similar non-acceptable results. I put about 25% more glass into the pot, fired at 1700 for 90 minutes, 1500 for 60 minutes, 900 for 3 hours and continued to cool slowly. I measured enough glass to have between 8 – 9cm. I also got tons and tons of bubbles. I don’t want to give up but I just don’t know what else to do.