Glassware Cracks

bio · Working Bee

Here's one for you Primathon;

Is there a way to either fix or check those small "stars" that sometimes develop and inevitably end up spreading?

2spun · The Resistor

Swiy,

use's Mapp gass,
swiy as well'd had use'd pices of the same type glass to mend,
swiy belives tho it fourms an un-untiy in the overall structure of your glassware,
leaving it not as strong. swiy would use'd mapp gass as long as there is no missing pices in the area that needs to be mend'd, swiy would heat up the whole glassware befor concertration on the area of question tho.
swiys not a pro but he has mend'd many ckacks.

bio · Working Bee

OK, I have acetylene air "turbotorch" setup which is a little hotter than MAPP, I think.
Also have Oxygen and the normal small welding nozzles. Brazing is about all I've done with it.

So if I understand correctly the piece would be preheated in an oven to as hot as home ovens go I quess then the star or other crack has the concentrated small flame directed at it until it fuses together. Does the spot just need to go to the softening point or almost melt?

So then you have had good luck with not annealing the piece (pyrex) after repairs??

methyl_ethyl · Riedel De Haen

I would question the integrity of any "repaired" glassware under high vacuum.

The few dollars spent on a new flask is a small price to pay in comparison to having 500mL's of double distilled ketone imploding and sending shards of glass into your face, and ketone onto the floor.

just a thought

m_e

2spun · The Resistor

I would question the integrity of any "repaired" glassware under high vacuum.

as well as i.

but for other uses, swiy has not had any real problems.
use'n a acetylene air "turbotorch" in the area of question after preheat may cause an indention, you should bee able to see the star mend it's self together, if you get an indention i'd blow it back out.
again as M_E said for the price of new glassware for pressures inward or outward would be preferd

just remembered
the size of your torch-head plays a big role as well,
as the size of the glassware your want'n to repare, if your glassware is large you really need to preheat it in uniform or your cracks can spred and get out of control

bio · Working Bee

Yes, methyl ethyl, bio has plenty of unblemished 24/40 and wouldn't think of even heating a scratched boiling flask much less placing under vacuum!!!

Having said that I just can't bear throwing glassware out the window because of some minor blemish so I use it for non critical room temp things like making my roach bait from the NaBO2 byproduct of a certain reaction.
Hell, my chipped 4L heavy duty Pyrex beaker 4 years later still operates. Priced one of these puppies lately?

.........use'n a acetylene air "turbotorch" in the area of question after preheat may cause an indention, you should bee able to see the star mend it's self together, if you get an indention i'd blow it back out................

I have a tiny one used for 1/4-3/8 inch copper and such that should work, I hope.I doubt I could blow a dent back out though if I made one. Thanks for the tip.

Lab suppliers sell diamond files for checking small chips and such in beakers and erlenmeyers.

http://www.vwrsp.com/catalog/product/index.cgi?object_id=0006656&class_id=5003901

* Never Discard Chipped Glassware Again

Save your glassware, recover beakers, and preserve your flasks with this handy industrial diamond file. Half-round shape smoothes sharp and jagged edges. Makes chipped glassware safe for use. Also may be used to score glass tubing. Nonslip faceted handle for ease of use. File diameter: 0.6cm (1/4"). File length: 10.2cm (4"). Overall length: 20.3cm (8").