Sconce question

[AndyT]

If you were to make a sconce shaped like the pic and it was about 40" tall and 20" across and was divided into several sections, how would you make a pattern for the glass so that it would slump properly?

[Bert Weiss]

Make a model out of clay or whatever material you can manage to form. Then make a castable refractory mold, or a wetfelt mold.

[AndyT]

Make a model out of clay or whatever material you can manage to form. Then make a castable refractory mold, or a wetfelt mold.

We had a local clay place make a full size mold and then they are going to cut it into about 12 sections. I then want to slump glass pieces or maybe drape them...I just don't know how to figure out how to cut a pattern and then trace it on the glass then slump or drape.

[Warren Weiss]

Andy,
Why do you want to cut the clay mold in 12 pieces? Just pour the castable (like Mold Mix 6) over the clay mold. Use a cylinder to act as a mold containment for casting. The clay mold should come out of the casting. You may want to spray Pam vegetable oil over the clay as a release. As long as there are no undercuts it should work. When dry, drill small holes around the bottom of the casting for air escape. Slump into the mold. You may have to do it in several small steps. If you try draping you WILL get folds. You will have to work out the size and thickness of the blank for that degree of slump. You will need a wide ledge at the top of the casting to prevent your blank from drooping over the sides and getting caught. You may have to trim off the lip of the final piece with a diamond band saw or ring saw. Copying a machine cast piece like that is not easy. Will probably require several test blanks 'till you get it right. You may want to practice with cheap window glass, but the temperatures will be different for the Bullseye or System 96. Good luck.
Warren

[Bert Weiss]

Make a model out of clay or whatever material you can manage to form. Then make a castable refractory mold, or a wetfelt mold.

We had a local clay place make a full size mold and then they are going to cut it into about 12 sections. I then want to slump glass pieces or maybe drape them...I just don't know how to figure out how to cut a pattern and then trace it on the glass then slump or drape.

I hear you. I think the answer is guess. You have 2 approaches I can think of, either make it bigger than you need and cut it to shape after bending, or keep guessing until you get the right shape. I think you have to slump not drape. I have seen people figure out how to slump something sort of like this in one piece and then cut it up.

[AndyT]

Make a model out of clay or whatever material you can manage to form. Then make a castable refractory mold, or a wetfelt mold.

We had a local clay place make a full size mold and then they are going to cut it into about 12 sections. I then want to slump glass pieces or maybe drape them...I just don't know how to figure out how to cut a pattern and then trace it on the glass then slump or drape.

I hear you. I think the answer is guess. You have 2 approaches I can think of, either make it bigger than you need and cut it to shape after bending, or keep guessing until you get the right shape. I think you have to slump not drape. I have seen people figure out how to slump something sort of like this in one piece and then cut it up.

My kiln is only 21 x 21 so trying to do this in one piece won't work. And my client wants to assemble all the sections with 1" wide copper strips that he will make. Yes...I agree that slumping would be better but then the glass won't have a high shine.

[Warren Weiss]

Andy,
If he is going to assemble it with copper strips, that is a horse of a different color. You may be able to do it in 12 drapes, which as you said will give you the shiny outside.
Warren