Originally Posted by MrOH
it's the thin, white layer. The middle, murky layer is just stuff that hasn't had the chance to settle yet. you can always cold crash and wash again to get rid of more trub, if you so desire.
I also just washed yeast for the first time today, and followed the steps in the yeast washing sticky (link
). I thought the dead and dying yeast sank with the trub, and the healthier yeast stayed in suspension longer. This allows you to "wash" the yeast (i.e. physically separate the healthy yeast from everything else) sequentially such that you end up with mostly healthy yeast in your mason jar.