When I first decided I wanted to work with glass, I also decided that the very first thing I must do is build a furnace. I would use the furnace to melt the glass, which I would then pour into a mold I had made using the usual lost-wax method. I had used the lost wax method successfully with bronze, so it seemed to me that it should work with glass too.
That’s really a mistake. I can be fun to pour glass, but glass is nothing like bronze. The big difference is viscosity, glass is super viscous. It takes minutes to pour glass from the crucible, and during that time, the glass cools so rapidly that only half of it pours before everything stops and the glass is stuck.
It isn’t like honey, where you can just wait for it the flow eventually — or if you are impatient, then just heat the honey and it will flow like water. Glass is different. Heat it to 1500F, and it won’t pour. Heat it to 1800F and it barely pours. Heat it to 2000F and it will pour, but freeze up within 20sec. Glass blowers deal with it, with their glory hole.
Regardless, this is really fun! The furnace is bright and beautiful. This isn’t casual. It is so hot, anything flammable will ignite instantly, including people. Take care what you want.