Flask question

[Gfunk]

I just bought a 2000ml flask and boiled some water in it to check it out. Is it common do have some real small pit holes in side the bottom of the flask? There pretty much hard to see, I only saw them when the boiling bubbles were coming out of them. I'm just worried about it cracking on me.

 

[theredben]

No need to worry. Just don't dump boiling hot flasks into ice cold water. Anything else borosilicate glass will handle.

 

[solavirtus]

I agree with theredben. Those flasks (as long as you bought a quality one) are meant to handle very high temps, and little areas of unsmoothness are perfectly normal. It really shouldn't crack with normal use.

 

[winnph]

No need to worry. Just don't dump boiling hot flasks into ice cold water. Anything else borosilicate glass will handle.

Strange you say that, because that's exactly what I do when I make a starter. Kill the flame, then place it into an ice bath to cool. I thought they could handle that kind of temperature swings pretty well... am I wrong?

 

[Gfunk]

Right on guys, I was worried there for a sec. I bought the morebeer 2000ml yeast starter kit. Feels like it's pretty heavy duty.

 

[Homercidal]

Mine has flow lines and pits on the outside. I usually let my flask cool for a minute or two before placing in the ice water and so far so good. I cant imagine that the minute or two is making that much of a difference. I've also heard of flasks breaking that way, so I always try to do it in a careful manner like covering with a small towel to catch the flying shards.

 

[VegasBrew]

My daughter is in collage to become a doctor and she has a lot of lab classes. She told me they actually scratch the inside bottom of the flasks in order to make nucleation points for the bubbles to form. It makes it easier to control the boil and see changes in things they are heating/boiling. Just make sure to let it sit for 30 seconds or a minute before you put it in cold water and DO NOT let the cold water level get above the hot liquid level inside the flask or it can possibly crack.

VB

 

[winnph]

Just make sure to let it sit for 30 seconds or a minute before you put it in cold water and DO NOT let the cold water level get above the hot liquid level inside the flask or it can possibly crack.

Good to know, on both counts. I was definitely not careful on either point up to this point, but will be going forward.

 

[King of Cascade]

My daughter is in collage to become a doctor and she has a lot of lab classes. She told me they actually scratch the inside bottom of the flasks in order to make nucleation points for the bubbles to form. It makes it easier to control the boil and see changes in things they are heating/boiling. Just make sure to let it sit for 30 seconds or a minute before you put it in cold water and DO NOT let the cold water level get above the hot liquid level inside the flask or it can possibly crack.

VB

I have been putting my flask directly into an ice bath right from the stove for the last 15 years. I have heard people say not to do this but it has never been an issue for me. If it makes you feel better or you think it makes a difference to wait a minute or two that is your choice.

 

[devilishprune]

I've taken a few lab class myself, and the flasks we used (usually kimax, kimble, or pyrex) were fine to take from boiling on a hot plate to being submerged totally in ice water. I would be more suspicious of cheaper brands, but I haven't had any problems in my experience.

The reason that I would think not to let the water level get above the liquid level in the flask is because it will float and could possibly spill.

 

[VegasBrew]

I do agree somewhat with taking you flask from direct heat strait to ice. I have a used pyrex flask that came from the UNLV lab dept. I know it is good quality so I can and do, go from heat to ice without worry however, not knowing what kind others have, I recommend waiting a bit to be safe.

VB

 

[iaefebs]

I just weighed a student grade 1 liter flask and a 1 liter lab grade flask. The student grade has imperfections in the glass, (pits and drip lines) and weighs 257 grams. The lab grade weighs 320 grams and looks perfect. I usually use the lab grade because it just feels safer to use. But I've used both. I never have gone from boil to ice so I can't comment. I usually let it sit awhile and put them in tap water and exchange to fresh water then to ice. That being said I most recently boil in a small saucepan and transfer to a jar and onto the stir plate. I find it less stressful on boil overs. I know I could use Fermaid or whatever but hey rdwhahb.