Bending glass (slightly OT)

[David Duke]

I have a design for a clock that I'm building that will require curved glass. Awhile back I saw a show on the Discovery Channel that showed the process of bending flat glass, it went somewhere along this procedure

Have a bed of sand, in the sand use a board cut to the desired profile/curve drag it across the sand making an indention (much like when pulling concrete down flat with a drag). Lay the glass across the profiled sand bed, heat to the required temperature in a furnace allowing the glass to sag/bend to the profile made in the sand, slow cool.

My question is what is the temperature needed to achieve glass movement, I have tried an internet search without much luck except in finding the temp for tempering glass which I believe is about 650/700*C or around 1200/1300*F. Would this be about right for the bend? Also how long should the cool down period be, I was thinking 4-6 hrs.

I know this is way off topic but I have faith in you guys :D :D :D !!

TIA

[Jamie Buxton]

You might get there quicker by buying bent glass sheet and cutting it to size. Van Dykes is one source.

http://www.vandykes.com/product/02000786/

[John Bush]

Hi David,
My daughter gave me a Christmas gift certificate for a glass blowing lesson and I had a blast doing it last weekend. The molten glass is 2100+ deg F. and I'm guessing "slump" temperature would be 1500 to 1800 deg. F. The Glory Hole is a 2500+ deg oven that you reheat the Glob, er, piece of art at the end of the pipe in to keep working the piece to the desired shape. That's hot stuff and the glass glob would slump quickly if you didn't keep turning it. After we finished the pieces we "created", they were put in an annealing oven and kept a 900+ deg F. for 24 hrs to allow the glass to form the strongest crystaline form. If you get the chance you should try to do some glass art, but without the right equipment I think you would have a tough time getting the results you are after for your clock . Good luck, John.

[Perry Holbrook]

David, bending glass is one of the things I do every day in my studio. It is done in a computer controlled kiln similar to a potters kiln. The molds can be made of sand as you said or clay or stainless steel. I may be willing to bend something for you if you have enough money:D .

PM me if you are interested. You can see some of my work at kopperwood.com.

Perry