5000ml narrow mouth erlenmeyer flask with flat bottom

5000ml narrow mouth erlenmeyer flask with flat bottom

Required: 1

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Never use any flask directly on an electric stove with coil elements without some form of heat diffuser. The concentrated heat can crack the flask making for an ungodly mess that will ban you from doing anything brewing related in the kitchen ever again.

Ensure that the flask has a flat bottom otherwise it is more likely that the stir bar will not spin properly.

You can boil a starter directly in the flask over a gas or ceramic/glass stove however, but it's recommended that a laboratory grade flask be used. Why? Most reasonably priced flasks are only 'student' grade and may contain tiny air bubbles that can cause the glass to shatter at extreme temperatures. One workaround to this is to place the flask in a saucepan with a few inches of water. Doing so allows you to use any grade flask on any stove-top (including electric stoves with coil elements) as the temperatures will not be as extreme.

We prefer to boil starters in a small 3.5 quart saucepan on a small portable induction cooktop right in the brewery, and then pour the wort in to a flask that is already partially filled with some sanitized/chilled water. This flask is first placed in our commercial stainless sink, so that if something was to happen the wort goes down the drain.

Hint: When you're done making a starter and want to get the stir bar out for a second starter or before you pitch, use a rare earth magnet on the outside of the flask to pull it up the side. While there's no harm in accidentally dumping the stir bar into the fermenter (we've all done it), you will inadvertently forget it's in there and end up pouring it down the drain when you go to clean the fermenter. That's why it's always good to have spares. ;)

For complete details see our Making a Yeast Starter article.

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