Sciencemadness Discussion Board

DIY Glassware Repair

MichiganMadScientist - 20-8-2013 at 11:34

Hello There:

I'm trying to develop a side-hobby of DIY glassware repair. I have a baseline knowledge regarding how the process is done in university glass-repair shops, and the type of equipment, etc. involved.

I tried using google to give me some more detailed information/instruction, but I found more hits from companies offering repair services than anything else.

I am curious to know if any members here have dabbled in DIY glassware repair and could point me to some more detailed instructions.

Example: "What kind of torch is best for annealing borosilicate?" (propane? MAPP gas???).
:)
Thanks for your help.

[Edited on 20-8-2013 by MichiganMadScientist]

[Edited on 20-8-2013 by MichiganMadScientist]

Pyro - 20-8-2013 at 11:39

You will need an O2/propane or an O2/acetylene torch to be able to properly work with borosilicate glass

Mailinmypocket - 20-8-2013 at 12:21

I found the post by Zan Divine to be particularly useful in the thread "repairing star cracks. Good luck! :)

[Edited on 20-8-2013 by Mailinmypocket]

Thanatops1s - 20-8-2013 at 19:51

Quote: Originally posted by Pyro  
You will need an O2/propane or an O2/acetylene torch to be able to properly work with borosilicate glass


As a former glass blower, I'd have to recommend oxygen/propane. A good torch is expensive, personally I mostly worked on a Carlisle CC but that's like an $800 torch. For about half that price, I really like the Nortel Redmax, I worked on one for a couple years. Also, if you're working with glass that has already been annealed, you're going to want to slowly bring it up to working temp in a kiln so you don't stress it too much.

Honestly though, I wouldn't recommend trying to work glass that has already been annealed. Yes it might work, but the odds of it cracking are pretty good and even if it doesn't, it will never be as strong as it was.

I should add though that I always worked on stuff with color and occasionally dichro so dealing with nothing but clear glass might be a little easier.

[Edited on 21-8-2013 by Thanatops1s]

jock88 - 21-8-2013 at 04:01


Why are glass blowing torches so expensive?

Would not welding torches or heating torches (available from welding supply housed) do the same job at one tenth the price.

You should be able to work in a limited capacity with a forced air + fuel torch for borosilicate.

watson.fawkes - 21-8-2013 at 05:20

Quote: Originally posted by jock88  

Why are glass blowing torches so expensive?

Would not welding torches or heating torches (available from welding supply housed) do the same job at one tenth the price.

You should be able to work in a limited capacity with a forced air + fuel torch for borosilicate.
Briefly, in order: Lots of machining, no, and very limited.

Making heat with flame is always a specialized proposition. Welding torches use acetylene as a rule because the flame temperature is higher. Working bulk glass, you don't even want that high a temperature (because the glass itself will start reacting) but you do need a lot of heat energy. Welding affects a smallish HAZ, the heat-affected zone, where with lots of glass processes, bends for example, you need to heat the whole of a portion of the work.

Carlisle etc. glass working torches put out a large amount of heat over a broad area, rather than a high temperature at a single point. Furthermore, oxygen and acetylene mix easily, but oxygen and propane do not. Special torches for propane that use injection mixing are available in the welding world, while that's ordinary for glass torches. Check the price for an injection torch for a more apples-to-apples comparison. They are, as you might guess, more expensive to make. Furthermore, glass torches have an extra requirement to block some of the radiant heat from the operator, hence all those fins on the body. And there's lots of internal porting you can't even see.

With forced air and propane, you're cooling off the flame significantly with all that inert nitrogen in the atmosphere. Indeed, air injection is used in some fancy devices to lower the flame temperature for annealing. So you'll need a lot more flame to raise the temperature enough to work, and it only works on small tubing.

jock88 - 21-8-2013 at 15:54


Someone on this site mentioned that very little glass work was performed by members.
Needing to purchase glass blowing torches that seem to start at hundreds of dollars is a good hinderence.
I made a mcLeod gauge yonkers ago using a oxypropane cutting torch + borosilicate glass. It the the first and just about only bit of glass wear I made.

You can get these cutting torches (and welding torches) for feck all on ebay


http://www.ebay.com/sch/i.html?_odkw=&_osacat=116642&...

you just need to then buy the propane head.

http://www.ebay.com/sch/i.html?_odkw=cutting+torch&_osac...

The welding heads (not the cutting head) will also burn propane even though they are designed for acetylene. They will give pointed flames compared to proper glass blowing torches.
Arranged in a crossfire (which is best for beginners I believe) they make a passable glass working flame.

Nothing going to beat proper glassw blowing torches but at the OUTRAGOUS prices they come at its no wonder people don't dabble with glass work.

Dr.Bob - 21-8-2013 at 18:31

Also, note than once you glue the joint together, it will hard to ever repair, as you need clean glass to repair it. once there is glue there, it will char in heat and the glass won't fuse. Same with grease and other stuff, but they are easier to clean off.

dontasker - 23-8-2013 at 23:36

I would strongly recommend this guy's videos:
www.youtube.com/user/glasslinger

He shows off some amazing talents for hand-making vacuum tubes/valves. It's not lab glassware, but there are some amazing tips that would be very valuable.

[edit]
Forgot to add this:
http://tubecrafter.com
[/edit]

[Edited on 24-8-2013 by dontasker]