Starting a Yeast Bank
With the availability and selection of both dry and liquid yeast, why would you want to start a yeast bank?
Well, perhaps you have a really awesome house strain that you want to keep forever before it mutates any further.
Also, I've been burned in the past when I wanted to make a really awesome doppelbock and found out that the yeast I need for it is only available for September.
And yeast strains get discontinued. At the time of this writing, Wyeast is discontinuing a bunch of Pilsner and American lager strains. While you can reuse a strain up to 6 times before it starts to mutate, with a properly maintained yeast bank, you can keep that going almost indefinitely.
This first gallery will show you how to prepare a house strain that you cultured yourself and don't want to mutate further. If you're planning on starting from a smack pack, skip to the second gallery.
If you've already got a yeast colony started or are using a smack pack, start reading here.