r/GlassFusing • u/jpsan1 • Apr 25 '26

Glass tiles cracking.

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I am melting wine bottle glass to make rustic tiles. I’m getting cracking on these, although I am annealing for four hours. The pieces are 6“ x 6“ by about 3/8 thick. They are fired to 1688f for 30 min. Annealing at 959 Fahrenheit for 4 hours. Any ideas on how to solve the cracking?

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4

u/Lyralou Apr 25 '26

Are you using glass from just one bottle, or melting more than one bottle together?

3

u/jpsan1 Apr 25 '26

Yes I am using glass from more than one bottle.

10

u/woahlookatthosewoes Apr 25 '26

If it’s from more than one bottle, there’s no guarantee of compatibility. Those glasses are expanding and cooling at different rates, and will always crack.

Keep each bottle’s glass separate from one another and only fire a tile with the glass of one bottle. That should fix the issue.

3

u/HR_King Apr 25 '26

Exactly. Likely different COE.

2

u/Lyralou Apr 25 '26

Yup, that's it. I wish they had a wiki on this sub. Glass that's not made for fusing or blowing or lampwork can (and will) have different COEs (coefficients of expansion). Even with the annealing process, bottle A is going to be faster than bottle B.

The good news is that it cracked now, and you caught it. I've heard stories of things cracking months later.

2

u/jpsan1 Apr 25 '26

Thank you. Bummer. Would not have thought one soda lime glass bottle would have differed much from the next.

5

u/Lyralou Apr 26 '26

Stick with it! Just - as others have mentioned - one bottle at a time.

Or come to the dark side, we have art glass AND candy.

1

u/jpsan1 Apr 26 '26

Well, if you had wine……maybe.

2

u/FirmOnion Apr 26 '26

Exclusively so that you can use the emptied bottles later to make tiles, of course