Step 6: Kiln cast glass
Close furnace and turn the heat up to 800C.
Leave it in there for six days.
We also put some little ceramic boats with extra glass chunks in the furnace, just so that we'd have some visual feedback.
(We did 900C for 12 hours, but our glass didn't turn out very pretty. The six-day figure is from this source: http://www.glasskulls.com/asending-sequence/)
The last picture shows our graphite crucibles disintegrating all over the furnace. That's why you should use a different material, I guess...
When you're casting metal, you can just quench your investment in cold water and it will pop right off, giving you access to your pieces. However, glass cracks when cooled too quickly, so you'll have to let it slow cool. Turn your furnace off and let it sit until it returns to room temperature.