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Author: Subject: fixing cracked glass / glassblowing
Yttrium2
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[*] posted on 22-6-2020 at 20:54
fixing cracked glass / glassblowing


My retort has somehow developed a crack around where the stopper connects. I am wondering if I can heat the area till red with a torch to seal in the crack or will this stress the glass? I mean does the entire retort need to be heated to prevent stressing the glass? They do have those giant torches for killing weeds, how well do those work for blowing glass? - I may need to heat the entire vessel to get rid of the crack..


Also, how do you tell if a glass is stressed? Somewhere earlier I was reading of a way to determine if a glass is stressed and will shatter later on from improper annealing



any advice on this topic greatly appreciated.

[Edited on 6/23/2020 by Yttrium2]
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Chemetix
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[*] posted on 22-6-2020 at 23:05


The quick answer is is yes with a maybe. There's a bit more to go over than a few posts can cover. PM me and I'll guide you through what you need to know and what equipment you might need. There are technique variations that you can use depending on the available equipment, so if you tell me what sort of equipment you might be able to get your hands on then I can suggest which technique is likely to succeed.
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Belowzero
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[*] posted on 22-6-2020 at 23:26


Quote: Originally posted by Chemetix  
The quick answer is is yes with a maybe. There's a bit more to go over than a few posts can cover. PM me and I'll guide you through what you need to know and what equipment you might need. There are technique variations that you can use depending on the available equipment, so if you tell me what sort of equipment you might be able to get your hands on then I can suggest which technique is likely to succeed.


I'd be interested too , please consider doing this in the public square :)
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wg48temp9
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[*] posted on 23-6-2020 at 01:38


You may want watch a glass repair video by Codyslab:

https://www.youtube.com/watch?v=86X5f9xprQ4

Its probably more about the problems of repairing a cracked flask so its a how not to do it video for repairing cracked flasks. I have seen a more successful video from an experienced glass blower but could not find it. I have tried it myself with mostly similar problems to Cody ie the crack propagating. Ideally for boro glass you will need at least an oxy propane torch.




i am wg48 but not on my usual pc hence the temp handle.

Thank goodness for Fleming and the fungi.
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Ubya
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[*] posted on 23-6-2020 at 03:20


propane alone won't work probably, to fix a star crack on one of my little flasks i had to use oxy-propane from a small torch, otherwise the glass is not hot enough to flow.

this process stresses the glass, you can see the stress spots with a polarizing filter and an LCD screen





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Chemetix
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[*] posted on 23-6-2020 at 15:46


I'll get a video up on how to repair cracks.

In case you missed the first video, glassblowing for complete beginners, have a look. https://www.youtube.com/watch?v=BjX5JwOvKGM

You can use the bunsen and blow tube technique to heal cracks on small pieces. For bigger pieces with thicker walls you'll need a small oxy- fuel brazing torch. Jewellery torches or plumbers torches will work.

Codys lab failed using a welding torch because of a few techniques he missed. I'll show you why in the video.
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XeonTheMGPony
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[*] posted on 23-6-2020 at 16:20


I use a map torch for most my glass stuff, propane turbo torch for smaller tube work.

I greatly miss my smith little torch HVAC edition it was perfect for that shit!
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Chemetix
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[*] posted on 24-6-2020 at 21:23


You can check out the video on how to heal small cracks I've posted on youtube.
https://youtu.be/MiW7vDJofeA

It's quick and dirty, but gets the point across. Hope it helps.
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Belowzero
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[*] posted on 25-6-2020 at 06:35


Quote: Originally posted by Chemetix  
You can check out the video on how to heal small cracks I've posted on youtube.
https://youtu.be/MiW7vDJofeA

It's quick and dirty, but gets the point across. Hope it helps.


Very nice video, thanks for the effort!
Gives me a lot more confidence in repairing my cracked condensor. The illustration of the polarization is really useful and quite obvious once shown like this, not so much just reading it from paper.

I am pretty sure people on youtube will like your content , you have a very clear way of explaining and a calm over you that makes it comfortable to watch.
Okay enough with the feathers :)
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wg48temp9
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[*] posted on 25-6-2020 at 16:58


Quote: Originally posted by Chemetix  
You can check out the video on how to heal small cracks I've posted on youtube.
https://youtu.be/MiW7vDJofeA

It's quick and dirty, but gets the point across. Hope it helps.


Having watched your first video how you get the scratch to propagated a crack round a glass tube by touching the scratch with molten glass. I figured the same thing happens when you heat the centre of a crack to repair it.

Thanks for the two videos.




i am wg48 but not on my usual pc hence the temp handle.

Thank goodness for Fleming and the fungi.
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Yttrium2
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[*] posted on 25-6-2020 at 19:09


can anyone explain how strain develops in glass?


Is this the best cheap polariscope that money can buy?


Would a bunsen burner be a good torch as opposed to the ones that screw onto the propane tanks that do not adjust? - My guess is yes, (would it be a good purchase?)
and in addition to the bunsen burner, I need a bunsen burner control valve regulator?

[Edited on 6/26/2020 by Yttrium2]

delete2.jpg - 16kB

[Edited on 6/26/2020 by Yttrium2]
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