Washing yeast - where's the yeast?

The top portion will contain a suspension of yeast. The best portion is the white layer (barm). The lower dark portion will contain much viable yeast but also the trub and dead yeast cells. A sanitized spoon will allow you to scoop out the best white stuff, but it will also create a contamination possibility.

 

Why not let all the yeast settle out first? Then, just before your next brew, you can decant the clear upper portion and use the rest for your batch. The amount of trub is minimal and should not affect the next beer noticeably (there are ways to minimize the amount of trub before bottling). I usually let the yeast settle in the fridge for about 3 or 4 days until the top layer is clear. I understand that the most healthy yeast is the yeast that is latest in suspension.

Note that not all yeast produce the same order of layers. I've had some highly flocculant lager yeast that drops well before the trub (literally drops in only a few minutes). Thus, with these yeasts the trub layer can be above some of the yeast layers.

 

As @OldBrewer says, this will settle out completely in several days. The liquid portion can easily be poured off. The layers of solid can not be separated (in my experience), I wouldn't even try. There will be trub, hop sediment, yeast (live and dead), and probably more things in those layers, hopefully all is sterile as you'll be pitching it all.

Consider making a larger starter than you need the next time you buy new yeast. Pour off the excess and all the solids that settle in the jar will be yeast cells only. Ideally this will more represent the strain's characteristics, plus the yeasties will never have suffered the stress of fermentation.

 

Here's what it will look like in less than a week:



This is trub'less, made from a new packet and saved for next brew day. And the good ole Mason jars even have a measurement scale built in . . .

 

Here is a great yeast calculator that has an overbuild feature built in - it is very handy, and sooo much easier than 'washing' yeast !

http://www.brewunited.com/yeast_calculator.php

 

I've never had a negative effect from a few tablespoons of trub. I typically aim to decant the thin top layer, pour in the good stuff, but not worry too much when some of the trub winds up in the fermenter.