I managed to chip the edge of an old Pyrex glass lid to an eight inch rectangular storage container. Is there a way to smooth the sharp edge it left on the lip of the lid- or at least make it not sharp so it's usable again?
I've got a Dremel tool and an assortment of wheels/disks but I'm not sure if Pyrex glass can be polished.
A diamond bit will do a great job. It helps to keep it wet so you do not create a hot spot but Pyrex is not as sensitive to that anyway. Regular old crocus cloth will knock the edge off if you have the patience. That is what we used for the 2 weeks that "bottle cutters" were popular in the 70s.
I've had good luck and bad luck, fire polishing using a torch with a pencil point flame. I actually did it successfully to a pyrex 1 cup measuring cup. I've also, on other occasions, gone too far and had the glass crack from too much heat in one location.
I recall using a metal screen to smooth edges in the lab but not sure so started googling and got this:
I don't think Pyrex is harder or much harder than normal glass. Any abrasive that scratches glass should work.
Art Todesco posted for all of us...
Flame on Art!
Thanks all, I should get to it by the weekend and I'll report back.
A Dremel mounted fine stone smoothed it pretty well but magnifier inspection showed what look like very tiny hairlines radiating away from the original chip. I've concluded it's not safe for food storage and deep-sixed it. Thanks for all the suggestions!
I used a butane torch to smooth a chip in a pyrex bowel. It seemed to work. The chip was no longer sharp. I let it cool and then tool it to the sink to wash. As soon as the water touched the bowel, it cracked the entire bottom out of the bowel. So...I cannot recommend using flame to smooth a chip in Pyrex!
May have worked if you brought the entire bowl up to some fairly high temperature, more than your oven.About 850 and cool for hours.
Heating one spot in glass until it starts to melt will create stresses, which your instructions may remove. I used to do some scientific glass blowing with Pyrex and everything made went into an annealing oven, which does just what you said. When using the pieces an end would be cracked off a cylindrical piece and the crack could be fused back together leaving uniform stresses around the cylinder.
Pyrex used to be a particular borosilicate glass. Pyrex is a brand name, and the owner now uses the name for a different kind of glass, not as low expansion.
Use something like silicon carbide paper to smooth a sharp edge.
On Thu, 29 Dec 2022 21:45:43 -0600, bud-- posted for all of us to digest...
+1I had a relatively new set of French White casseroles. I found out the hard way (I cut myself, picking up the lid) that one lid had a sharp edge on the rim underneath. I don't know how; if it came that way or if I splintered off a piece of the glass. Anyway, after reading a suggestion that sanding would work, I pulled out a painting sponge/sander and worked on it for a couple of minutes. The sharp edge dulled right away and it looks like it will be safe to use now.
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