I have a drinking glass with a small chip in the rim (1/4" wide, 1/16" deep). It’s an Iittala Aino Aalto tumbler, FYI (the blue one, at top left).
I keep using it, because I like it (and have more in the set), but I know I’ll eventually carve my lip open on the sharp edge when I’m not paying attention.
Can I use a propane blowtorch (i.e., the kind I use for brazing copper plumbing joints) to smooth this sharp edge? Or will I likely crack/explode the glass, do nothing to it, etc.?
I think what you want is one of these.
Filing down the sharp edge is much less likely to damage the glass, a blowtorch is not the right tool for the job.
If you are incredibly careful and judicious with the blowtorch, then theoretically you could smooth the edge without cracking the glass or deforming it.
My advice is don’t even try. And if you don’t take that advice, practice on some cheap glasses you don’t care about.
Yes, as matt says, it’s very difficult and takes patience and practice. Even then, good results are NOT guaranteed. I wouldn’t try, unless it’s a throwaway.
If you’ve got a blowtorch burning a hole in your pocket, give it a shot, but I’d agree with others that filing is your better bet.
I’d even try filling the chip with some kind of non-toxic epoxy before lighting up the torch.
Your chipped place doubtless has several microscopic, or nearly so, cracks so you have to heat the glass veeeeeeeerrrrrrrry slowly to avoid spreading the cracks or cracking the glass elsewhere because of differental expansion from temperature differences.
If you are going to throw the glass away unless you can smooth the chip give it a try. Otherwise I would try the mild abrasive method.
And cooling the glass down afterward is nearly as touchy as heating it up.
No.
People used to grind off the chip. Try emery paper or a polishing stone.
Glass is very hard to work with amd getting it aroung 1500 F I think is to dangerous. Glass also explodes during heating under certain conditions. The stuff they use for blowing chemistry equipment and little figuring in the Dells, is not what you get in a drinking glass.
A little drop of SuperGlue ™ will seal the rough parts and a second drop can fill the indentation. I’ve done this before. If it doesn’t work for you, then you can file/sand it smooth.
That never occurred to me. I might have to buy some cheap glasses at Salvation Army and chip them just to play with it.
If you’ve got a blowtorch burning a hole in your pocket, you have more pressing issues . . . :dubious:
And if you’ve got Prince Albert in a can, LET HIM OUT!
Wanna-be glassworker here (took some fusing and lampworking classes) . . . I would be very leery of using any sort of unknown glass in a blowtorch flame. Better to go the file route.