Can I cool float glass faster?

hoknok · Post by **hoknok** » Mon Jan 19, 2004 11:10 am

OK, I know that slow annealing is needed for glass but how slow is slow?

I am using float glass, 1/8 inch thick, sandwiched 2 and 3 layers thick. I have a large 22 c ft kiln and fire with three shelves all loaded. My kiln is very well insulated and will cool down after 700 deg at about 33 deg/hour. This is with the vent holes open and a vent fan going. This seems slow to me for the type and thickness of glass I am doing currently.

Is this about the right speed others experience? I am tempted to crack open the lid about an inch.

What is the temp you read when "its cool enough to touch"? Are you opening the kiln up at 200 Deg. I guess I am looking for a way to see the stuff faster but obviously do not want to thermal shock everything.

Paul Tarlow · Post by **Paul Tarlow** » Mon Jan 19, 2004 12:17 pm

When you say you are using three shelves do you mean side by side or stacked?

If stacked, your schedule will need to go much slower than with a non-stacked arrangement in order to maintain evenity.

- Paul

hoknok · Post by **hoknok** » Mon Jan 19, 2004 1:35 pm

I have three shelves in the kiln stacked with about 8-10 inches apart. The kiln is side and bottom fired.

Paul Tarlow · Post by **Paul Tarlow** » Tue Jan 20, 2004 12:15 am

hoknok wrote:I have three shelves in the kiln stacked with about 8-10 inches apart. The kiln is side and bottom fired.

Stacked shelves like that are going to require you to go exceptionally slowly since you want to keep heat even and you've got multiple layers of shelf between the top-most items and the bottom elements.

I wouldn't even know where to start.

- Paul