[rjharper]

To add to the great advice so far, as a former lab chemist, I'd use a Pyrex flask on a gas stove or ceramic top electric, but certainly not on a coil, for the hot spot reasons mentioned. It won't work on an induction top, because that requires cookware with ferromagnetic properties.

All that said though, every time I've tried to use the erlenmeyer directly, I've had awful boil overs! 

[oldmankaufman]

I've been making starters directly in Erlenmeyer flasks for a couple years now. Some on an electric coil stove, but never directly on the coils. Use some sort of diffuser between the coils and the flask to avoid the hot spots. Mine was a doubled up, perforated aluminum thing sold as a "double boiler". Takes forever to get to a boil, but at least you get good control of the heat to limit boil overs. I've switched to a small Coleman propane camp stove that screws directly onto the bottle and have had pretty good success provided the flask is adequately sized. I had a 500 ml crack using this small burner but 1L and 2L flasks have been good to go with the heat output available.

As for the boil overs - It is best to keep your initial volume of wort to about half the total flask volume Then 5-6 drops of a foam control agent per 1L of wort usually keeps the foam inside the flask, even with Wheat DME.  Don't forget the stir bar before you start the boil if you've got a stir plate. As someone else here mentioned, Cold bar+hot glass=unhappy brewer.

Also consider using a "lab thermometer"  (cheap glass type) pushed through a foam stopper and into the wort during the boil and ice bath. It's one slick, sanitary way to make sure you hit your pitching temp.

[coastsidemike]

Is it necessary to prepare starters with a full boil?  Avoiding the flask boil-over is hard to manage, and realizing I never thought to use a smaller burner.  Seems like sanitation-wise being above 180 is necessary, and thus holding in the 195-200+ degree range should be more that sufficient.

[Jimmy K]

Is it necessary to prepare starters with a full boil?  Avoiding the flask boil-over is hard to manage, and realizing I never thought to use a smaller burner.  Seems like sanitation-wise being above 180 is necessary, and thus holding in the 195-200+ degree range should be more that sufficient.

The steam from boiling will sanitize the walls and whatever foam/foil cap is on the flask, which is convenient but can be accomplished other ways too. I've been bringing it to boil and then removing from heat and allowing it to cool slowly. I'm sure it stays above 180 for quite a while this way. Steam sanitizes very quickly, so a few seconds should do it.

There is a difference between sanitation and sterilization. If you want sterilized wort, I'm not sure 180 would do it. But if you'll only use the yeast in a single batch, sterilized wort isn't needed.

[narvin]

+1 to foam control!  I use a flask because it's one vessel, no mess, and there's nothing to sanitize, but a boil over definitely ruins that.

[Stevie]

I use an electric stove with a Lodge cast iron skillet as a defuser. Works well. I am still searching for the magic  temperature setting between "taking forever" and "wort on the ceiling"

[davidgzach]

Glass top stove, 5L Bomex Erlenmeyer and a drop of fermcap.  Heat to boil and directly to ice bath.  Zero problems, many starters.....

Dave

[klickitat jim]

I'm still a fan of pressure canned starter. Wicked easy. Always waiting for me in the pantry.

[morticaixavier]

I'm still a fan of pressure canned starter. Wicked easy. Always waiting for me in the pantry.

yup.

I just captured two new strains of saison yeast a couple weeks ago because I had a few jars of wort in the pantry ready to go. easy peasy.

[klickitat jim]

I have some pils malt laying around that needs to be used, and a weekend coming where I won't have room in the fermentor freezer, so I'm going to mash and can two cases of 1.030 pils

[Jeff M]

I'm still a fan of pressure canned starter. Wicked easy. Always waiting for me in the pantry.

Can you describe the process?  Every time i make a start i end up boiling over from my flask, then you have to chill etc. it just becomes a horrible process.

[klickitat jim]

Sure. I put 3 oz of DME in each quart jar. I fill with warm water to an inch from the top. I wipe off the mouth and put a new canning lid on. I shake till there's none stuck to the bottom. I adjust the lid ring to finger tip tight. From there follow your pressure canner instructions. I process mine at 20 psi for 15 min.
 
I usually make this on a non brew day and can up a case or two.

Wort ends up about 1.035 which is great for building buddies. On the day I make my starter I sanitize my flask, stir bar, a funnel, and a chunk of foil. I put the yeast in and a couple quarts of premade wort. Bingo.

[morticaixavier]

Sure. I put 3 oz of DME in each quart jar. I fill with warm water to an inch from the top. I wipe off the mouth and put a new canning lid on. I shake till there's none stuck to the bottom. I adjust the lid ring to finger tip tight. From there follow your pressure canner instructions. I process mine at 20 psi for 15 min.
 
I usually make this on a non brew day and can up a case or two.

Wort ends up about 1.035 which is great for building buddies. On the day I make my starter I sanitize my flask, stir bar, a funnel, and a chunk of foil. I put the yeast in and a couple quarts of premade wort. Bingo.

I actually do this even when I'm not planning on storing long term, minus the pressure part. I just process in a water bath. If you do it a night or two ahead of time it's perfectly safe to leave it on the counter or pop it in the fridge.

Or mash a couple extra pounds on the next AG brew and run off the last bits into quart jars and pressure can. If you are making a 1.050+ beer you probably don't even have to add any grain, just run an extra gallon of near boiling water through your grain after your last batch (or last runnings)

[Jeff M]

Awesome sounds pretty neat.  course ive never had to process anything through a water bath, thank god for them internets!