Erlenmeyer Flask Cracked

[kgranger]

So I was preparing a yeast starter today, I put the water in, then some DME, sat it on my stove and turned the burner on. 2 minutes later, I hear a crack and catch it just in time. This picture happened. Any thoughts as to why? I've used this flask for many starters, and always boiled the wort right in the flask on the stove with no problems. It's an erlenmeyer flask, so shouldn't it be able to be heated and cooled without any problems?

 

[NervousDad]

Was it an electric stove?

 

[shanesherman]

Yeah, I do it all the time. Looks like you had some bad luck or a flawed flask.

 

[kgranger]

It's a gas stove. I mean I guess it's just bad luck. Could it maybe have something to do with the fact that I used cold water in the flask? I can never remember, but I think I've always done that. It's just crazy, those burn marks. Maybe should I have started the stove at a lower setting?

 

[pdietert]

Borosilicate glass (pyrex, schott, etc) can still crack under thermal shock. It has about 1/3 less thermal expansion than regular glass (soda-lime glass). It did crack because of the cold water and high heat.

 

[microbusbrewery]

I've heard of people occasionally having problems using them on electric stoves. I have a gas stove too and do the same as you; cold water plus DME then heat to a boil. My best guess is it was a defective flask. I suppose the glass could weaken over time from the heating and cooling cycles.

 

[hunter_le five]

I've heard of people occasionally having problems using them on electric stoves.

Mine cracked the very first time I tried to heat it on an electric stove. Never doing that again....

 

[kh54s10]

On an electric stove it is usually the coil type. The bottom of the flask heats unevenly, hot on the coil and cooler in between.

In the case of the OP I would suspect the cold water was heated too quickly stressing the glass. I would also think it is normal that the flask would have a limited number of heating then cooling cycles.

 

[nickmv]

It's easy to fix the issue with electric stoves. Get some heavy duty aluminum foil, and form a square with it, about 3-4 layers thick. Then place that between the flask and the actual burner. It helps distribute the heat evenly, and won't stress the glass anywhere near as much as direct contact.

Source -- I've been doing it for years. Only broken 1 flask ever, and it was in the sink, not on the stove. I accidentally banged it with a glass.

 

[ccleve1]

I use a gas stove with a heat diffuser just to be safe. So far I've never had a problem. You can pick up a diffuser cheap


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[orangehero]

I would warn against using aluminum foil on a ceramic cooktop, it can melt and stick on there forever.

I think the problem is that you were using a cheap, bottom-of-the-barrel, chinese junk flask. There are usually lots of flaws in the glass and they will crack easily. Spend a little more money and buy name brand borosilicate glassware if you want durability.

 

[MaxStout]

Borosilicate glass flasks are meant to be heated over gas flames. That one likely cracked due to a flaw. There are lots of "factory seconds" of lab equipment out there, and I'll bet that flask had a scratch or bubble in the glass.

Pay the $$ and get a Pyrex or Kimax brand flask.

 

[ObsidianJester]

Hard to tell for sure by the picture but it also looks like at least to me the DME was not dissolved in to the water? If there was a lot of DME that was mostly solid at the bottom of the flask it would create scorch marks too possibly if it is not stirred. Not saying that is the cause but if there was something burning (Sugar) and there was cold water on top of it I could see it stressing a weak flask.

 

[Spartan1979]

Borosilicate glass flasks are meant to be heated over gas flames. That one likely cracked due to a flaw. There are lots of "factory seconds" of lab equipment out there, and I'll bet that flask had a scratch or bubble in the glass.

Pay the $$ and get a Pyrex or Kimax brand flask.

I had one off brand flask and it cracked the first time I was heating it.

Only Pyrex or Kimax for me, too.

 

[kombat]

Why not just heat/cool the water/DME in a regular metal pot, then pour the (chilled) wort into the flask? That way the flask isn't enduring repeated heating/cooling cycles, thus stressing it.

How many threads about cracked flasks do we have to see before people stop pressing their luck applying high heat and rapid cooling to glass vessels? Is it really worth the 15 seconds it's saving you from pouring from a pot into the flask?

 

[Ilan34]

Why not just heat/cool the water/DME in a regular metal pot, then pour the (chilled) wort into the flask? That way the flask isn't enduring repeated heating/cooling cycles, thus stressing it.

How many threads about cracked flasks do we have to see before people stop pressing their luck applying high heat and rapid cooling to glass vessels? Is it really worth the 15 seconds it's saving you from pouring from a pot into the flask?

This is how I do it seeing as I have an electric stove. Granted, you have to clean the pot too, but making a starter still seems like a cakewalk timewise compared to bottling or brewing.

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[petrolSpice]

Why not just heat/cool the water/DME in a regular metal pot, then pour the (chilled) wort into the flask? That way the flask isn't enduring repeated heating/cooling cycles, thus stressing it.

How many threads about cracked flasks do we have to see before people stop pressing their luck applying high heat and rapid cooling to glass vessels? Is it really worth the 15 seconds it's saving you from pouring from a pot into the flask?

It's nice to boil, cool, and ferment everything in one vessel to avoid the hassle of transferring liquids, dirtying up extra pots and funnels, and the greater possibility of infection.

Another way to do it would be to boil the wort in a pot, then transfer it to the sanitized flask immediately. The still hot wort should help avoid infection during the transfer. It may be worthwhile to preheat the flask before pouring in the wort to reduce the thermal shock.

Since I'm using a regular glass jug (from a $9 3L bottle of crap wine), I boil and cool in the pot then transfer to the sanitized jug.

 

[microbusbrewery]

I had one off brand flask and it cracked the first time I was heating it.



Only Pyrex or Kimax for me, too.

This got me to thinking...I don't think I've ever noticed a brand on my flasks. I got all of them at my LHBS. Do the name brand ones have a brand/logo on them? I've never had one break (except when my dog knocked one to the floor) but I wonder if mine are cheap Chinese made ones.

 

[MaxStout]

This got me to thinking...I don't think I've ever noticed a brand on my flasks. I got all of them at my LHBS. Do the name brand ones have a brand/logo on them? I've never had one break (except when my dog knocked one to the floor) but I wonder if mine are cheap Chinese made ones.

Yes, both Pyrex and Kimax brand glassware will have their respective names on it.

 

[MannyZ]

In this particular case I'm with ObsidianJester in thinking the dry clump of DME is the cause. Looks like it acted as an insulator allowing portions of the glass to become extremely hot while adjacent sections were in contact with liquid and still cool.

Not saying I wont suffer from broken glass at some point but I do make sure my DME is thoroughly mixed in before turning on the stove and I start my burner on its lowest setting then slowly ramp up in order to minimize the risk.