Erlenmeyer Flask - Pyrex vs Other material

[ArcLight]

An Erlenmeyer or Conical Flask can be made of various materials.
From what I've read the Erlenmeyer flasks most people use are thin and they break if one is not very careful. (I mean even bumping it or setting it down not roughly but not very gently, obviously not dropping it)

1) It seems the Pyrex costs a lot more than the non Pyrex - Is it worth it?


I also see wide neck flasks sold (whereas Erlenmeyer flasks have a narrow neck). I plan on using aluminum foil instead of an air lock (to allow some gas transfer).

2) Does a wide neck have any disadvantages/advantages vs. a standard Erlenmeyer flask? Like the bottom not being flat and interfering with the stir bar?

3) For a 2 liter flask is a 1 inch stir bar the correct size?


Given how delicate I hear these are, I plan of cooking the starter mix in a small pot and cooling it in the pot, then transfering it to the flask. I'd be afraid to cook it (with gas) then give it a couple of minute sto cool down , before placing it in water. Or can it handle that - no problem?

 

[Tall_Yotie]

The wide necks make it easier to pour in your starter solution and yeast, and generally easier to handle and work with. A wide neck should have nothing to do with how flat the bottom of the flask is.

A 1" stir stick should be fine for a 2L flask.

I HIGHLY suggest against cooking in the flask. The glass means that there are no cavitation points, so when you stick a stir bar in there and the fluid is still really hot it will volcano out. I burned my hand really bad doing this. Cook in a pot, cool it down to the ideal temperature, and then transfer it to a sanitized flask.

It can take the heat no problem, this is what they are meant for. But tossing it in cold water when the glass is hot will cause it to shatter on you.

As for the flasks being brittle, the ones I have (2L and 5L) are pretty damned beefy. With anything glass you have to practice caution and good handling. I see no reason to specifically go with Pyrex brand other than that they have a good reputation. But honestly, and glass erlenmeyer flask should do.

 

[ArcLight]

I HIGHLY suggest against cooking in the flask. The glass means that there are no cavitation points, so when you stick a stir bar in there and the fluid is still really hot it will volcano out.

It can take the heat no problem, this is what they are meant for. But tossing it in cold water when the glass is hot will cause it to shatter on you.

1. can I cool the starter mixture with the stir bar in the flask? Will that heat damage the stir bar? Or cause the coating to react? Some are Teflon coated, Teflon shouldn't be burned, but its only 212 degrees, not 400.


2. How much does the starter mix need to cool down, so that it wont shatter the beaker? If the beaker sits for 5 minutes is that sufficient? Maybe then place it in warm water to lower the temperature a bit, but not too much, then put it in cold water. (55-65 degrees?)



(Or maybe just cook it up in a pot, cool it, and pour it in thru a funnel - I just have to clean up 2 extra items and sanitize the funnel.)

 

[Patirck]

I always cook in a pot, cool and pour it through a funnel into the flask. Yes you have to sanitize the flask and the funnel but not a big deal. Another advantage of cooling in the pot is to leave some of the break material behind in the pot this way. I know it probably doesn't matter at all but at least I know that the stuff on the bottom of the flask is pretty much all yeast an not break material from the wort.

 

[Tall_Yotie]

ArcLight,

Cook the starter solution in a pot. Cool the pot down to pitching temperature (65F-72F generally). Put the solution into the flask. Put the stir bar into the flask. Make sure the flask and the stir bar are sanitized (Star-San or similar). I suggest using the funnel method, it saves the concern for shattering the glass.

I don't know exactly what temperature the heat shock would cause shattering of the glass. I can't really give a "this much time" comment as that doesn't mean much as far as temperature, and false information could lead to serious injury.

Don't cook the stir bar. Usually it is teflon coated plastic of some sort. Scientific ones tend to be meant for high temperatures, but there is no reason to add the stir bar in before it is needed to be used.

Mix u pa couple cups of sanitized water, pour some into your flask, swirl to sanitize, then pour out. Dip the stir bar into the sanitized water, put it in the flask, cover with a piece of aluminum foil. Once the pot with the starter solution is cooled pour it into the flask using a funnel that has been rinsed with the sanitizer & water solution. Pitch in the yeast, cover again with the aluminum foil, stick it on the stir plate and you are good to go!

 

[nickharbour]

The bottom is more flat on the Pyrex. The cheaper ones shouldn't be a problem though as long as you are on a very level surface. Took me a few tries of experimentation to find the best place to put mine.