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Back Magic and slumping

Posted: Thu Apr 01, 2004 8:59 pm
by Ross Mayfield
I have some plates that I want to brighten the botton of. I plan to use Back Magic and to cure it at 1000. Then I want to slump them at 1250 for 1&1/2 hours. Can i do this with the cured side against the mold with out a problem?

Re: Back Magic and slumping

Posted: Thu Apr 01, 2004 9:03 pm
by Brock
Ross Mayfield wrote:I have some plates that I want to brighten the botton of. I plan to use Back Magic and to cure it at 1000. Then I want to slump them at 1250 for 1&1/2 hours. Can i do this with the cured side against the mold with out a problem?


What do you mean, "brighten"? Are they dull now? A very nice finish is to sandblast, then slump. At the right temp the back will become a matte sheen. 1250 is hot for me, for a slump but YMMV. The hotter, or longer, the slump, the more texture the back will pick up from your mold. Brock

Posted: Thu Apr 01, 2004 9:12 pm
by Ross Mayfield
Brock The texture is ok but there is a dullness about the piece that I thought to brighten. Actually they were already slumped but did now get to the desired shape. The temp then was 1225 and the time was 45 min. I understand that successive slumps require longer time and higher temp. Is this correct? What happens to the Back Magic at this higher temp?

Posted: Thu Apr 01, 2004 9:32 pm
by Brock
Ross Mayfield wrote:Brock The texture is ok but there is a dullness about the piece that I thought to brighten. Actually they were already slumped but did now get to the desired shape. The temp then was 1225 and the time was 45 min. I understand that successive slumps require longer time and higher temp. Is this correct? What happens to the Back Magic at this higher temp?


It's not necessarily correct, you already have lot of heat work on the piece, and should be able to re-slump it at or near the original slump temp, with some more time.

I think this successive slump/higher temp thingy came about years ago from people like Tim O'Neal slumping into successively steeper molds. He made bowls back in the 80's, that were very steep, by this method.

I've never used Back Magic, there seems to be people pro and con. Brock

Posted: Thu Apr 01, 2004 11:02 pm
by Stuart Clayman
I have used back magic and have never had any luck with it.. read old posts.. Recently I was told it did work for someone when the piece was very smooth... but the problem is the smooth side was the side that was up, not the back side.

Back Magic and Slumping

Posted: Fri Apr 02, 2004 1:27 am
by Ross Mayfield
I appreciate the ideas. Guess I will have to rethink the situation. By the way, am I the oldest amaetur on the board? --76 --and still fusing and slumping.

Posted: Sat Apr 03, 2004 12:00 am
by Lynne Chappell
Someone please correct me if I'm wrong, but I thought that Back Magic and Bending Glaze shouldn't come in contact with anthing. I know they have to be fired with the glaze up, but can you then put them against a mold on a subsequent firing without problems?

Posted: Sat Apr 03, 2004 12:53 am
by Cynthia
Lynne Chappell wrote:Someone please correct me if I'm wrong, but I thought that Back Magic and Bending Glaze shouldn't come in contact with anthing. I know they have to be fired with the glaze up, but can you then put them against a mold on a subsequent firing without problems?


That is my understanding as well Lynn. Back Magic is intended for use on already slumped work and you can mature it at temps that are too low to cause the piece to start to bend.
It will pick up the primer from the mold and your shiny back will be encrusted permanently with primer if you put it on and then bend into the mold.

Bending Glaze is intended to be put onto the surface (upside...top) of the glass before slumping/bending and should mature to a high gloss at the low bending temps. Both contain lead...which is why they mature at low temps.