Back Magic and slumping

This is the main board for discussing general techniques, tools, and processes for fusing, slumping, and related kiln-forming activities.

Moderators: Brad Walker, Tony Smith

Post Reply
Ross Mayfield
Posts: 5
Joined: Sun Mar 09, 2003 5:18 pm
Location: McCall, Idaho

Back Magic and slumping

Post 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?
Brock
Posts: 1519
Joined: Mon Mar 10, 2003 1:32 pm
Location: Vancouver, B.C.

Re: Back Magic and slumping

Post 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
My memory is so good, I can't remember the last time I forgot something . . .
Ross Mayfield
Posts: 5
Joined: Sun Mar 09, 2003 5:18 pm
Location: McCall, Idaho

Post 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?
Brock
Posts: 1519
Joined: Mon Mar 10, 2003 1:32 pm
Location: Vancouver, B.C.

Post 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
My memory is so good, I can't remember the last time I forgot something . . .
Stuart Clayman
Posts: 224
Joined: Mon Mar 31, 2003 12:35 pm
Location: Virginia
Contact:

Post 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.
Kiln Repair by a Clayman kilnrepair@yahoo.com
Glassworks by a Clayman
http://www.GlassArtists.org/GlassworksByAClayman
Ross Mayfield
Posts: 5
Joined: Sun Mar 09, 2003 5:18 pm
Location: McCall, Idaho

Back Magic and Slumping

Post 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.
Lynne Chappell
Posts: 186
Joined: Fri Mar 14, 2003 2:05 am
Location: Surrey B.C. Canada
Contact:

Post 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?
Cynthia

Post 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.
Post Reply