Bert Weiss wrote:
What I really want to discover is just how thick a slab of glass I can anneal on the floor of my kiln. Eventually I will get around to doing comprehensive testing on this. I can borrow the necessary equipment for the tests. I just need a compelling reason to do the tests, beyond curiosity.
Last summer at Pilchuck some people were doing pieces close to two inches thick in sand beds. The sand holds so much heat it helps annealing. I don't think anybody was covering their thick pieces with fiber blanket to anneal, but that would help.
Bert Weiss wrote:
What I really want to discover is just how thick a slab of glass I can anneal on the floor of my kiln. Eventually I will get around to doing comprehensive testing on this. I can borrow the necessary equipment for the tests. I just need a compelling reason to do the tests, beyond curiosity.
Last summer at Pilchuck some people were doing pieces close to two inches thick in sand beds. The sand holds so much heat it helps annealing. I don't think anybody was covering their thick pieces with fiber blanket to anneal, but that would help.
ch
Charlie
On my recent trip to Portland OR, I used a Kenny Simpson designed bell kiln. It was similar to my design, but there were a few big differences. That kiln had an element in the floor and they raised a 2" thick HD board shelf off of the floor. there is also an element that runs around the perimeter walls set below the shelf top. These 2 elements are designed to add heat in order to deal with heat loss through the floor.
This was at John Groth's Studio. John rigidized his HD board kiln shelf and meticulously ground it flat and smooth. He also routinely rolls out thinfire paper for his bottom surface. I have never seen a flatter or smoother firing surface. Personally I am interested in a not smooth bottom as I like the textures I get. BTW this kiln and shelf is a 6 or 7 footer, (I forget) Big HD board shelves (up to 9' I think) can be obtained through special order.
Ray Alghren explained to me that he thought that my 1.5" fusings might be as thick as my design would allow. I have never tried thicker so I don't much know. I did cut 3 layers of 1/2" float fused together with my glass cutter and a framing hammer. Bang bang and it broke right along the score and blew me away. That is my idea of annealed well enough.
I can see that a sand bed would help reduce heat loss by simply retaining heat.