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Warning: Borosilicate Erlenmeyer Flask not THAT strong...

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MDVDuber

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Remember too that any scratches etc will weaken the glass and it'll be more prone to break.

We used to do a soil test back in school that involved heating samples in a sand bath to some pretty high temps. We'd always do it in the hood cause that sand would scratch the pyrex over time and every once in a while we'd have a catastrophic failure - think pyrex and sand exploding all over the place. On the bright side it did convince the lab manager to purchase new equipment from time to time...
 

jamest22

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Not all borosilicate glassware is made equal. Teaching grade E-flasks go for around $50, while the research grade E-flask we buy at the university chem store cost us $70-100. As with anything you get what you pay for. I suspect research grade glass is a little thicker to withstand being handed down from PI to PI over successive years, while teaching grade reflects the disposable nature of most classroom equipment.
+1 I went through two run of the mill 5 liter flasks before I picked up a Pyrex brand 4 litre erlenmeyer. The Pyrex is clearly thicker and the inside bottom is so level and smooth my stir bar no longer makes a rattling noise.

I also use my flask on a banjo burner but I keep it really low, never letting the flame touch the flask. I also start super low and slowly raise the flame until it gets boiling as not to heat shock the glass. Regardless my first two cheap 5l flasks cracked on the burner(which is one reason id NEVER use it on an inside stovetop)
but the Pyrex is still going strong.
 

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The brand name Pyrex and no longer is an indication of borosilicate glass. Beware. This is especially true of modern cookware.
 

emjay

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The brand name Pyrex and no longer is an indication of borosilicate glass. Beware. This is especially true of modern cookware.
As far as I'm aware, this doesn't apply to labware. At least, I've never seen Pyrex labware that's actually tempered soda-lime glass (or any brand for that matter).
 

emjay

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+1 I went through two run of the mill 5 liter flasks before I picked up a Pyrex brand 4 litre erlenmeyer. The Pyrex is clearly thicker and the inside bottom is so level and smooth my stir bar no longer makes a rattling noise.

I also use my flask on a banjo burner but I keep it really low, never letting the flame touch the flask. I also start super low and slowly raise the flame until it gets boiling as not to heat shock the glass. Regardless my first two cheap 5l flasks cracked on the burner(which is one reason id NEVER use it on an inside stovetop)
but the Pyrex is still going strong.
It might be on low, but a banjo burner is almost certainly putting out wayyy more heat than a stovetop. These things are meant for use with stuff like bunson burners… a stovetop can emulate that far more easily than a banjo burner. If you're REALLY that concerned, use a double-boiler type setup. It might be a bit slower, but nothing like doing a full boil with wort, or heating water for an infusion/sparge.
 

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As far as I'm aware, this doesn't apply to labware. At least, I've never seen Pyrex labware that's actually tempered soda-lime glass (or any brand for that matter).
Corning sold the brand name Pyrex a while ago. It has caused some people 'problems' in the cookware end. Look at this page where they tout the virtue of soda line over borosilicate. Nowhere do I actually see them say that their product is either. It sure sounds like they are giving warnings that would be made more necessary for soda lime though.


http://www.pyrexware.com/index.asp?pageId=30


Is Borosilicate glass safer or better than soda lime glass?

While both borosilicate and soda lime are appropriate for bakeware, tempered soda lime is more resistant to breaking on impact, which is the leading cause of injury from using glass bakeware according to national emergency room data. Both soda lime and borosilicate bakeware can experience thermal breakage if exposed to sudden or uneven temperature changes. You can avoid the most common causes of thermal breakage by following four simple rules:

1. Always place hot bakeware on a dry, cloth potholder or towel.
* Never place hot bakeware on top of the stove, on a metal trivet, on a damp towel, in the sink or directly on a counter.
2. Never put bakeware directly on a heat source such as on a stove top, on a grill, under a broiler or in a toaster oven.
3. Always allow the oven to fully preheat before placing bakeware in the oven.
4. Always cover the bottom of the dish with liquid before cooking meat or vegetables.
 

emjay

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Corning sold the brand name Pyrex a while ago. It has caused some people 'problems' in the cookware end. Look at this page where they tout the virtue of soda line over borosilicate. Nowhere do I actually see them say that their product is either. It sure sounds like they are giving warnings that would be made more necessary for soda lime though.


http://www.pyrexware.com/index.asp?pageId=30


Is Borosilicate glass safer or better than soda lime glass?

While both borosilicate and soda lime are appropriate for bakeware, tempered soda lime is more resistant to breaking on impact, which is the leading cause of injury from using glass bakeware according to national emergency room data. Both soda lime and borosilicate bakeware can experience thermal breakage if exposed to sudden or uneven temperature changes. You can avoid the most common causes of thermal breakage by following four simple rules:

1. Always place hot bakeware on a dry, cloth potholder or towel.
* Never place hot bakeware on top of the stove, on a metal trivet, on a damp towel, in the sink or directly on a counter.
2. Never put bakeware directly on a heat source such as on a stove top, on a grill, under a broiler or in a toaster oven.
3. Always allow the oven to fully preheat before placing bakeware in the oven.
4. Always cover the bottom of the dish with liquid before cooking meat or vegetables.
I'm well aware that their cookware is tempered soda lime glass... which really, is adequate for almost any kitchen, as long as you treat it properly. My post referred specifically to Pyrex labware.
 

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Had a brain fart today and after pouring my boiled starter in my 2L Mason jar I placed it in the sink filled with cold water. C R A C K.....
 

progmac

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bump with a bit of info -- i have been wondering about thermal shock with these, so i emailed corning about it. this is in reference to corning pyrex erlenmeyer flasks....

they said flasks made with their "7740" borosilicate glass can withstand temperature swings of 160C (320F) and can be heated directly over a flame, with a hot plate etc.

this was good news for my process, which is boiling my starter wort in a pan and pouring the boiling water into a flask and then transferring that to an ice bath.

i believe there are different grades of glass out there. hope this info is helpful for people.
 

Fermented_minds

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http://csmedia2.corning.com/LifeSciences/Media/pdf/glass_care_safe_handling_RG_CI_101_REV2.pdf

Follow the "Heating and Cooling" instructions on page 4 and use good ole common sense when heating/cooling things, and you shouldn't have any issues. Most of the lab-grade Pyrex, speaking from experience as a scientist, is 7740. It is pretty strong stuff and can take quite a beating if you treat it properly.

I personally never directly heat any of my vessels with an electric element or a flame. I'll either add media to a sanitized vessel, or autoclave media in the vessel at 121 C and 15 PSI for 15 minutes. It's the lowest strain on the glass.
 
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