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cracked in half

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Daryl Freed
Posts: 5
Joined: Tue Oct 14, 2014 2:59 pm
Location: Cooks Creek, Manitoba, Canada

cracked in half

Postby Daryl Freed » Tue Nov 01, 2016 5:34 pm

This piece cracked in half 1 day after coming out of the kiln. It is a mosaic piece made with Spectrum that I tack fused and was in the process of filling in the gaps with frit when I noticed that it had cracked in half. This has only happened to me once before and it was with a piece that was extremely similar in design and size and it also cracked 1 day after tack fusing. It is 16 to 21 inches in diameter. Any suggestion of why this has gone wrong would be greatly appreciated. Thanks
My schedule was
100 to 250 hold 30 min
100 to 1050 hold 60 min
100 to 1250 hold 60 min
300 to 1300 hold 4 min
AFAP to 950 hold 120 min
100 to 800 hold 30 min
100 to 700 no hold
300 to room temp


[img][img]http://i.imgur.com/zM8ZlFN.png[/img][/img]





Image

Warren Weiss
Posts: 140
Joined: Thu Mar 13, 2003 8:06 pm
Location: Richmond, VA

Re: cracked in half

Postby Warren Weiss » Tue Nov 01, 2016 8:21 pm

Daryl,
That is a very pretty piece, but a very complex one from a thickness variation standpoint. That will require extended annealing. How many thickness of base glass and was it fired separately to a full fuse? I don't understand the purpose of the many holds on the way up. I would suggest the following even without knowing about the base glass.
100 dph to 1050 (no holds)
200 dph to 1300-1325 hold 15 min.
AFAP (with the kiln closed) to 950 ; hold 2 1/2 to 3 hrs because of the wide variation in thickness.
80 dpf to 800 no hold
100 dpf to 700 no hold
Natural rate of cooling to room temp.
No peeking before 1100 on the way up or below 1200 on the way down.

Warren

Daryl Freed
Posts: 5
Joined: Tue Oct 14, 2014 2:59 pm
Location: Cooks Creek, Manitoba, Canada

Re: cracked in half

Postby Daryl Freed » Tue Nov 01, 2016 9:23 pm

Thanks Warren for the suggestion - it is 1 layer of clear with 1 layer of the opal glass. Some of the elements were prefired and a couple of very small elements are 2 layers

Warren Weiss
Posts: 140
Joined: Thu Mar 13, 2003 8:06 pm
Location: Richmond, VA

Re: cracked in half

Postby Warren Weiss » Tue Nov 01, 2016 10:49 pm

Daryl,
In that case, I would go for the 3 hr. anneal hold as that is a change from 2 to 4 layers adjacent.

Warren

DonMcClennen
Posts: 350
Joined: Sun Mar 09, 2003 9:09 pm
Location: Ontario

Re: cracked in half

Postby DonMcClennen » Wed Nov 02, 2016 11:43 am

What is the white mesh-like material in the background under the frit?? It may have caused some problems.
"The Glassman"

Daryl Freed
Posts: 5
Joined: Tue Oct 14, 2014 2:59 pm
Location: Cooks Creek, Manitoba, Canada

Re: cracked in half

Postby Daryl Freed » Wed Nov 02, 2016 6:53 pm

It is grippy shelf liner on top of a lazy susan sort of thing that spins around. Do you think that might be a problem? The piece does extend beyond the edges of the spinning thing. The bottom glass is a single layer and most of the pieces on top are 1 layer and a couple of the very small elements are 2 layers thick. So in a couple of places it goes from 1 layer to 3 layers thickness.

Warren Weiss
Posts: 140
Joined: Thu Mar 13, 2003 8:06 pm
Location: Richmond, VA

Re: cracked in half

Postby Warren Weiss » Thu Nov 03, 2016 12:09 am

Daryl,
I misunderstood your answer. I thought you meant the base was 2 layers (one transp. and one opal.) I would suggest that you pre full fuse 2 layers for the base and then add your design.
Warren

Daryl Freed
Posts: 5
Joined: Tue Oct 14, 2014 2:59 pm
Location: Cooks Creek, Manitoba, Canada

Re: cracked in half

Postby Daryl Freed » Thu Nov 03, 2016 2:44 pm

Sorry I guess that I didn't make it clear. What you first understood was correct. It is 1 layer of clear with 1 layer of the opal desigh. There were just a few of the small opal pieces that were prefused and are 2 layers. I really appreciate your suggestions with the schedule and next time I will anneal much longer.

Valerie Adams
Posts: 587
Joined: Mon Apr 19, 2004 2:49 pm
Location: Santa Rosa, California
Contact:

Re: cracked in half

Postby Valerie Adams » Thu Nov 03, 2016 11:22 pm

Because tack-fused elements form almost a 90° join instead of a smooth, full fused surface, the tension at those angles is extreme. Bullseye recommends annealing four times the length of time you'd normally anneal a piece, based on thickness. I see at least three layers in some places, so I'd anneal that piece four times the normal anneal time for a 9mm piece.

Sorry it broke; it was lovely.

Daryl Freed
Posts: 5
Joined: Tue Oct 14, 2014 2:59 pm
Location: Cooks Creek, Manitoba, Canada

Re: cracked in half

Postby Daryl Freed » Sat Nov 05, 2016 6:53 pm

Thanks Valerie. You are right - it is pretty much 90 degrees. Next time I will anneal 4X the usual time. I'm on to other projects for now but when I'm not so sad about it I will give that design another try.


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