Breaking glass while soldering

by Nicole Deslandes

I am soldering a large copper foiled panel.

What can cause breakage? I have two broken pieces and don't understand.

The breakage happened about 10 inches from where I was soldering at the time. I know that too much heat will break the glass, but from 10 inches away?

I am very upset because those two pieces are very intriquate and will be hell to replace.

I put everything on hold and won't touch it for a while

I don't want another broken piece if I am doing something wrong.

Thanks for your help.
Nicole Deslandes


I can't believe you're doing anything wrong with your soldering, I believe it all started at the cutting table.

Most often the breakage is cause by a small fracture in the glass that happens when you break it out. It will be so small that you won't see it until it starts to run during soldering.

Tapping is one way to cause these fractures. If you do tap the glass, I'd recommend using running pliers instead. There are very few cuts that can't be run with running pliers.

You mentioned that the pieces are very intricate. Did you cut them out with a saw or a glass cutter. If there are extreme angles, the glass will eventually run just because glass likes to break in a straight or gentle curve, not an angle. This is very true when using a glass saw. The fracture won't start to run until you start soldering.

You said 10 inches away. It may have started running when you soldered that area (still invisible to you), then continued as you moved the panel during the rest of the soldering.

Comments for Breaking glass while soldering

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Sep 20, 2012
Thermal Shock
by: Andrew

I come from an electronics background where much research has been put into soldering. I suspect the reason is uneven heating of the glass. The area being soldered expands more than the rest of the glass causing any imperfections or tiny fractures to run. This would be more prevalent where the glass is too cold.

When machine soldering it is normal to pre-heat the circuit board (or in this case glass) to 150 deg C or so before soldering to prevent thermal shock. Try popping the work in the oven or gently heat all the nearby glass with a hot air gun or hair drier.

Whatever the cause better cutting will certainly help.

Sep 12, 2011
Possible remedy for cracked glass pieces
by: Kathy

I also have run into this infuriating problem. Fortunately in my case I was able to cut small strips of foil to place over the crack both on the front and the back of the piece, and then soldered them. In effect, the line blends into the piece like any other solder line and nobody ever knows there is a crack underneath. Obviously this will not work with all designs, but maybe you will be one of the lucky ones and it will with yours.

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