I visited the glass shop today and got my pieces back from the last two weeks' classes. Here's the first of them from week 4.
It started out as a normal 7" diameter disc, made from leftover glass from my other projects. This one was going to be a drop ring, so I wanted to have some fun and put lots of details in; things going on visually, in order to see the forthcoming distortion. Lots of stringers (the long rods) and frit (tiny glass blobs) are the order of the day.
I visited the shop a few days later, by which time the discs had been fused, but not yet slumped. So here's what it looks like after fusing. This would apply to all the things I've made so far; they all start out flat like this and get slumped as a second stage.
On week 5 of our class (the final one), some of our drop rings were slumped during the class so we can see what it looks like. Mine was one of these. Here they are in the kiln with Sarah, our instructor, holding it open. She is wearing a Kevlar heat resistant sleeve, since the kiln is at 1325F (718C). You can see the rounded bottom ends of the glass pieces inside, glowing red. The lighter colour tall things are ceramic stands holding up the doughnut shaped moulds.
Here's the final product, after I brought it home earlier today. Mine slumped about three inches; not as much as some and a bit more than others. It depends on the glass, on how much it slumps over a given time.
Finally, here's a look down the inside. You can see how the stringers have curved into the shape of the bowl, and the frit has become elongated as it cascades down the sides. It's basically just a big ol' gravity well. The little lizard on the edge was a pre-cut glass piece in a shiny dichroic finish - file him firmly under "couldn't resist!" - I had to add him in there :-)
So now we know how glass will slump and fall when there's no support. Possibly a bit impractical, but certainly fun.