Trying to understand a break...

Barbara Muth · Post by **Barbara Muth** » Sat Jul 05, 2003 10:47 am

Firing some tiles in my kiln last night. All have been fired together twice before. They are composed of a tile in the middle, cut from some patterend glass and framed in black. BE glass. size 6x6 inches square. This was the flip and fuse, final fuse. 3/8 inch thick. Had been previously annealed with a 45 min soak at 960 and 100 dph to 700.

In this firing I went up 300 dph to 1000, soak 5, 500 dph 1250, soak 5, afap to 1425, soak 10, afap to 960, soak 45, 100 dph to 700, off.

On the way up one of the tiles broke in a classic s shaped curve. The edges of the break are nicely rounded.

Would this indicate that my tiles had not been properly annealed prior to this fusing? The fact that only one broke puzzles me. I would expect that if one was stressed, all should have been stressed.

(and doesn't this crap always happen when you are trying to finish up a delivery????)

Thanks for any and all comments.
Barbara

Mark Hughes · Post by **Mark Hughes** » Sat Jul 05, 2003 11:44 am

Was the tile that broke the closest to your peep hole?

Brock · Post by **Brock** » Sat Jul 05, 2003 12:00 pm

Barbara, when you say, "classic s shaped curve", do you mean a lazy S, or are there distinct curves, or hooks, at the ends of the break? The hooks denote a lack of annealing in a previous firing, the lazy s shape could be thermal shock. Your firing schedule is fine . . . sometimes things just happen for reasons we cannot deduce. Brock

Jerry · Post by **Jerry** » Sat Jul 05, 2003 12:29 pm

I agree with Brad. The fact that the edges of your break were rounded indicate the fracture occurred on the way up. That's a thermal fracture. An annealing fracture would have shinney edges because it occurred late enough that the edges weren't subjected to a lot of heat.

Don't think you can take this to the bank, but my experience is that glass is less forgiving the more times it's fired. I ALWAYS go slow going up in my second and third firings plus adding time for stabalization and annealing on the way down, and I mean GENEROUSLY!. After all that work, I'd rather wait to see what it looks like finished than take it to the land fill.

Jerry

Amy Schleif-Mohr · Post by **Amy Schleif-Mohr** » Sat Jul 05, 2003 12:48 pm

Jerry I think you are mis-undersanding Brock.

You can have annealing cracks on the way up if the piece is not annealed properly on the way down in the previous firing. Annealing cracks can show up long after a piece has been fired.

Amy

Stuart Clayman · Post by **Stuart Clayman** » Sat Jul 05, 2003 1:07 pm

What I want to know... does Jerry know something that we don't know? Are Brad and Brock the same person, just alter egos? or would that be altered

As for the thread that is goig on, there is nothing that I can add. I agree that the cause could be the prior annealing, and it could be the placement of that one, or it could be G-d or else the fusing gods keeping you humble. (Now then question is, if there is a fusing god,,, which of the 2 alter egos would be in that group?

Stuart

Brad Walker · Post by **Brad Walker** » Sat Jul 05, 2003 1:35 pm

Stuart Clayman wrote:What I want to know... does Jerry know something that we don't know? Are Brad and Brock the same person, just alter egos? or would that be altered

I'd better set this one straight. Brock and I are not the same person. We both wear glasses and our names start with the same two letters, but that's where the similarity ends. We live on two different coasts (in two different countries). I don't pay his bills and he doesn't pay mine. And (believe it or not) he actually writes posts and sends emails without my telling him what to write.

Having said that, I agree with Brock and Jerry and Amy, too. I'm really a very agreeable person.

But not a fusing god. I'm fairly certain that if there is one he (or she) posts on another board.

Barbara Muth · Post by **Barbara Muth** » Sat Jul 05, 2003 7:24 pm

Mark Hughes wrote:Was the tile that broke the closest to your peep hole?

Nope, it was actually furthest from the peep hole.

Brock wrote:Barbara, when you say, "classic s shaped curve", do you mean a lazy S, or are there distinct curves, or hooks, at the ends of the break? The hooks denote a lack of annealing in a previous firing, the lazy s shape could be thermal shock. Your firing schedule is fine . . . sometimes things just happen for reasons we cannot deduce. Brock

I am guessing thermal shock then. (see pic below). Puzzled, because I have done this many times, often firing them more than this one was fired. Some of the glass in this piece was in for the third time, the rest of the glass was being fired for the second time.

I was immensely surprised at this thermal shock, thought I was firing conservatively enough as this always works for me.

While many suggest that you have to take it easy on subsequent firings, the slowest ramp I have done was 200 dph for a 1/2 inch piece that eventually had 11 firings and an uneven surface. And it is still in one piece. So I didn't imagine that a 300 ramp would be too fast. Next time (this evening) I'll go 250.

You live and you learn!

Barbara

(at least it wasn't my WG@BE submission that broke!)

Amy Schleif-Mohr · Post by **Amy Schleif-Mohr** » Sat Jul 05, 2003 7:40 pm

Speaking of WG@BE, I was looking for some info on it. Is there a info section or do I need to look in the archives? I can't seem to find it, I could be blind.

Amy

Barbara Muth · Post by **Barbara Muth** » Sat Jul 05, 2003 7:58 pm

haven't seen anything on it in forever, just saw several months ago that it was in the works for this fall.

Brad Walker · Post by **Brad Walker** » Sat Jul 05, 2003 8:00 pm

Amy Schleif-Mohr wrote:Speaking of WG@BE, I was looking for some info on it. Is there a info section or do I need to look in the archives? I can't seem to find it, I could be blind.

No formal announcement yet. The exhibition will be in November. Most likely, entries will be due from mid August to mid September. We hope to coincide with the move to the new BE facility.

Amy Schleif-Mohr · Post by **Amy Schleif-Mohr** » Sat Jul 05, 2003 8:14 pm

K, thanks. I just needed to know approximately the time so I can plan. Hahaha, type A? Not me!
Amy

Tony Smith · Post by **Tony Smith** » Sat Jul 05, 2003 9:08 pm

Definitely a type A-"plus"

Tony

WarmGlass.com

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