Yeast from commercial beers

Can anyone give me an idea of how many bottles to gather yeast from? And the process...should I start small with like 100 ml then step it up to a full 1L starter?

i'd start with 3 or 4 bottles of dregs into 250 ml of 1.02 or so wort. when it's finished, crash and decant, pitch slurry into 500 ml of the same gravity, repeat process and pitch slurry into 500 ml of 1.04 or so wort. that should get you enough yeast to make the starter for the beer you'll be making. i did this with 4 bottles of Bell's yeast to get the yeast for the IPA i have in primary. :rockin:

Which of their beers did you get it from? I am going to clone a NorthPeak vicious wheat IPA, should i take the yeast from that one or should I lean toward one of their lower ABV beers?

i used the Bell's Amber, but the Best Brown and pale ale both have a good amount of yeast. there's a thread here, 'Yeast Harvest - Bell's Amber' or something like that, that has a bunch of useful info on the subject. there's also a lot of other threads on this that are quite helpful. the key is to start small and slowly step it up to pitching population. the first starter made from dregs will be sluggish, but as you step it up, you'll really start to see some growth. the method i suggested should get you the cell count you need. the IPA i did this on kicked off in 4 or 5 hours and went from 1.067 to 1.012 in 6 days.

edit: the thread i mentioned was bumped to the top of this forum a few mins ago.