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Author: Subject: Hairline Cracks / Scratches in Borosilicate Flasks
JJay
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[*] posted on 14-2-2016 at 23:44
Hairline Cracks / Scratches in Borosilicate Flasks


I just noticed that my 3L round bottom flask has several small hairline cracks or scratches. I don't remember noticing them previously. Are these anything to be concerned about?

(Oh, and I should mention it has only been used twice: once with a water bath and once with an oil bath.)

[Edited on 15-2-2016 by JJay]
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UC235
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[*] posted on 15-2-2016 at 10:54


Scratches are fine. I have some hideous glassware that I use regularly. Hairline cracks or star cracks you could continue to do room temp chem with relatively nonhazardous materials, but I would strongly advise against running anything at significant temperatures or under vacuum. There is no way to effectively fix them yourself unless you have glassblowing equipment.
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JJay
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[*] posted on 15-2-2016 at 13:11


They are small lines, about 1cm long. I'm not sure what it would have been scratched on but I suppose some sand could have gotten trapped next to it in storage/shuffling. I would hate to have to buy a new 3L boiling flask.
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Dr.Bob
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[*] posted on 15-2-2016 at 14:14


A crack will be clearly visible as through the glass if you look at multiple angles and such. Most, but not all, cracks in rbfs are star cracks, which are a 3, 4, or 5 pointed crack, looking like an asterisk or a cross (X, *, etc). There are occasions that I have seen a linear crack, but those are rare in round flasks. Scratches are not normally an issue for normal reactions in rbfs, I have flasks with lots of scratches from stirbars, rubbing with a spatula, or rubbing against other flasks. If they appear to just be on the surface, they are likely fine.

Now if you are doing anything really hazardous or under pressure or vacuum, then it matters more, and you will want to use a high quality flask. But for many normal reactions, a rbf is fine to have some scratches. I have seen people use ones with star cracks for non-vacuum work (I don't often use them for anything that matters, I save them for reactions that are really dirty and then toss them), and I have used some beakers and grad cylinders with minor cracks in them, some for many years without a problem. But I tend to do the same for them in many cases, use them for a PCC reaction or some polymer forming mess reaction and then toss them once they are too nasty to clean.
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alexleyenda
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[*] posted on 15-2-2016 at 14:32


Quote: Originally posted by Dr.Bob  
use them for a PCC reaction or some polymer forming mess reaction and then toss them once they are too nasty to clean.


I wish I had the chance to do the same for PCC reactions XD It's such a pain to clean after them.




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zed
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[*] posted on 16-2-2016 at 19:50


Scratches are OK.. But, monitor the situation.

Real cracks are an ever-present menace. You really don't want that baby to finish cracking, when you are refluxing a liter of ether, full of LiAlH4.





[Edited on 17-2-2016 by zed]
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