Fleaker
International Hazard
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Registered: 19-6-2005
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Cracked Glassware
Ok, I recently purchased 10 Duran bottles but when they arrived they has a small superficial crack on the base of the bottle. Not just one of the
bottles, but on every single bottle in the same exact place, there is a crack. I think it might have been from improper tempering (the cracks are that
close together).
Well, on to my question: how would I go about fixing these bottles? They're very nice excluding the crack on the base. I guess I'm
wondering that if I go to heat it up to melt it back together, will the glass crack upon cooling, even this high quality borosilicate? Thanks for any
advice/info from those of you who have experience with fixing broken glassware.
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12AX7
Post Harlot
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AFAIK, BS (heh) works just like any other glass and I'd imagine you can weld it back together. It does melt hotter than soda-lime and shrinks
less, but AFAIK you can't quench it or anything, nearly as much as quartz can, so you'll still have to melt it slowly, feather out stresses
and anneal if possible.
Tim
P.S. Now you know why they were liquidation sale price 
[Edited on 8-6-2005 by 12AX7]
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neutrino
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Make sure to anneal them afterward. This will prevent related cracking in the future.
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bio2
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I've had some success with smaller glassware (borosilicate) with stars and hairline cracks by preheating in the kitchen oven to as hot as it goes
then w/o removing the piece completely, melting the flaw together with a 000 or 00 Oxy/Acet welding tip using a carburizing flame.
If you have a better way to preheat then do it.
Annealing would be necessary if heating under vacuum or other rough duty.
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ayush
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Glassblowing for Laboratory Technicians
This is small book of over 2 MB useful for Glass Blowing Technicians. Enjoy.
| Code: | http://rapidshare.de/files/625500/glassblowing_for_laboratory_technicians_barbour.djvu.html
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Cloner
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I don't like the fact that there is no table of contents in that book, other than that it answers some questions I had myself.
No time to read it all now, but to the question of the initial poster: there is strain and stress in glass after the glassblower worked it. It is
usually put in an oven after working, and then with a lamp the glassblower checks out whether there are still stresses. UV or IR lamp, I forgot which.
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S.C. Wack
bibliomaster
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? The table of contents is 4 pages long.
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Primathon
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stress testing
Oxy/Propane is the preferred gas choice for working pyrex glass. As for stress testing, it's usually unnecessary after annealing a piece
properly in a kiln (~1040°F) and letting it cool. If you want to see/find the stresses, look up information on polariscopes (I think that's
what they're called). I've even see some DIY kits that just use polarized sunglass lenses in a creative arrangement to test for stress
points.
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Polverone
Now celebrating 21 years of madness
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| Quote: | Originally posted by Cloner
I don't like the fact that there is no table of contents in that book, other than that it answers some questions I had myself.
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If you aren't seeing the table of contents, you probably are using an older DjVu reader that doesn't deal properly with newer DjVu files. I
noticed out-of-order pages myself (so that the book would start with the first chapter and TOC was somewhere near the back) when using an older reader
with some DjVu files.
PGP Key and corresponding e-mail address
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Fleaker
International Hazard
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Well, my friend and I attempted a repair job using regular propane and an improvised kaowool kiln of sorts. The torch didn't have nearly enough
heat to do the job so either I'll have to get oxypropane or oxy hydrogen to try and melt it. It took the heat suprisingly well, an estimated
1600F was obtained and the glass didn't crack or shatter upon cooling.
I might try and use a PVC material designed for coating things to add a cushion for the base (and perhaps to reinforce it).
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bio2
Hazard to Others
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MAPP gas gets hot enough and is available in the little disposable cylinders.
Use a Turbo Torch type tip as they get quite a bit hotter than the standard ones, a couple hundred degrees IIRC
Speaking of MAPP; anyone try it for synthesis? Propadienes should react with damn near anything!
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