WarmGlass.com

Hi,

I was making a mosaic-like fused project yesterday. Basically, I put on a 12.25 inch white BU 113 a layer of broken pieces from a previous melt (average: 1/4 inch thick); the pieces were separated by 1/16 to 1/8 inch so that I could see the white base between them. The melt was made using BU clear, white, red and marigold.

It looked pretty good this morning when I opened the kiln (70F): the soft fuse gave me just the look that I was after. I set the blank on the slumping mold, put on some devit spray and when I came back, the blank was split in two

The schedule I used was:
200 1000 20
100 1250 30
* 1400 05
* 900 120
50 800 00
100 700 00

Obviously, this is an anneal break. How do you suggest that I adapt the schedule next time?

Any suggestions on how to use the leftover pieces? Gluing then slumping is not an option, from reading everal posts on this board.

Cheers!

Lucie

I'd suggest your AFAP down to 900 might not be a good idea... your speeding thru part of the anneal zone. go AFAP to 1000F then down to 900 at 50F deg/hr

What is your slump schedule??

Just as a side note; devit spray (I'm guessing you're using SuperSpray?) needs to be fired to at least 1400° in order to fuse clear. I accidentally used it on some tack-fused pieces that only went to 1380° and it rendered them splotchy and dirty looking. Typically, it's used during your fuse, not your slump.

Sorry for the confusion: I guess I should have mentioned that the schedule I posted was for a tack fuse. My blank cracked on the mold before I even programmed the kiln for the slumping...

I always thought that from a full or tack fuse temperature, it was AFAP to 900 as this was the (new) annealing target when using bullseye glass. I used to do AFAP to 960F. Should I go back to that temperature?

Lucie

Still ... what Valerie said: Were you going to use the devit spray on the slump step? I guess that doesn't address the crack problem, but just wanted to know if you had a secret way of divitting during slumping.

Beginner's luck I guess: I always used devit spray before slumping and everything comes out shiny.

But with stuff breaking for my last 3 loads, I guess Imy luck ran out

Are you sure the piece was completely cool? Could be you hit it with the devit spray and it cracked.

Long shot, but you never know...

Dana W.

sometimes in a pot melt you can have coe shift.......

when you pulled it out of the fuse was it totally cool?

your cool to 900 does not look like a problem to me.....

If it is a "tac fuse" with varying thickness that is probably the problem. Add more anneal for a piece like that......picture would help.

I would agree with Laurie, it's probably the anneal. You're tacking 6mm (average) onto 3mm, total of 9mm thickness with only a single layer in spots. Plus, you've got red and marigold that's being tacked onto a stiff glass like white, so you need to treat the glass as if it's at least 18mm thick and possibly as if it's 27mm thick. IOW, anneal for 3/4 or even a full inch of thickness.

Marigold is one of my favorite colors, use it a LOT, but it's a fussy glass in a tack fuse. It'll get even fussier, possibly even shift a tad, in a potmelt, so I'd give it a lot of room in the anneal schedule. Right now you've got an anneal soak that would work for 12mm of glass (1/2 inch), and a downramp that's closer to what you'd use for 19mm (3/4 inch) of glass.

I'd suggest getting consistent with them--try at least the 19mm schedule, which means a 3-hour soak, then 45 dph to 800, 81 dph to 700, 270 dph to room temp. Personally, I'd be even more conservative and go for the 1-inch schedule because of the marigold/white combination, but that's just me.

If you're still getting breaks with a 1-inch annealing schedule, then you may need to resign yourself to the notorious hot color COE shift. You can test it by melting a bit of your potmelt onto a piece of clear, running a very conservative anneal and checking it through the polarizer. If you see strong halos, schedule changing isn't going to help.

(remember, btw, that your mileage may vary--this is in my kiln, with my processes)

Thanks a million Cynthia! I really appreciate your response and especially, you taking the time to enlighten us, newbies!

I have another melt waiting on the sidelines to be fused in a panel. Of course, I used only red,marigold and white (I apparently love living on the edge for a newbie! ). I will follow your advice to a T, being definitely be ultra-conservative with the annealing, especially since that melt was most likely not annealed properly in the first place.

Lucie

Also, remember that this glass has to be warmed up REALLY REALLY SLOW
because it has probably not been annealed properly the first time.
Jim