I just harvested (WY1450) yeast from a mild to build up to a brown ale and then that will go into a RIS. I ended up taking a lot more than I typically do.
What’s the dark layer on top? Just beer stained yeast or is it trub? Keep it? Skim it and pitch the lighter bottom portion? There even seems to be a stratification within the bottom lighter yeast.
Looks like you picked up some trub along with the yeast but it also looks like there is some yeast mixed in there. You could dump off that top layer but I’d rather keep the beer above preserving the yeast and see a little trub get into the next beer than risk losing perfectly good yeast under a perfectly good preservative to ditch the trub.
This is getting pitched less than 24 hours from harvest so I could easily remove the top trub layer and have plenty enough for the batch being made today.
Thanks for the input!
You can, but I haven’t found any benefit to it. IMO, every time you mess with your yeast it’s just one more place you can screw something up, so why risk it if there’s nothing to be gained?
If it’s been crashed for 24 hours you can probably pour off most of the trub-y layer without disturbing the creamy yeast underneath. 100 mL is plenty to pitch into a 5 gal batch, even 10 gal at average gravity.
I ended up pouring off the majority of the dark layer right before pitching ~80 mL of the bottom yeast layer. That was probably the fastest start to fermentation I’ve ever had. Pitched at 64F after 90 seconds of the mix stir for aeration and I had active fermentation in 3 hours.
Denny, this went into your Noti Brown Ale recipe (although I had to substitute Fuggles for Willamette due to LHBS not having the latter). This is the first American brown ale I’ve ever made - looking forward to tasting this one! The mild I made with the first pitch of the WY1450 just got bottled and the hydrometer sample tasted great. I’m calling it a trans-atlantic mild as it has English malts and an American yeast. 
I would not have expected that type of stratification to occur with 1450. That phenomenon usually occurs when one is using a highly-flocculent yeast culture. The break usually settles before the yeast with most brewing strains.
I always have believed that in part this dark layer is hop isomer residue and well worth getting rid of if one re-pitches.
I make slightly larger (1 pint) larger starter than I need. I then swirl this at high krausen and harvest 1 pint just prior to adding to the fermenter. I usually take a little taste prior to doing this to make sure all is well. I have been very happy with this method…I don’t have to be concerned with what happened to the cake during fermentation…It’s clean and no hops flavors…
Starter harvesting does not produce the same effect as repitching. A culture does not begin to perform at its best until the third pitch into actual beer wort. Repitching places selective pressure on a culture. The yeast cells are subject to higher levels of hydrostatic pressure and ethanol as well as iso-alpha acids. Propagating laboratory grown yeast in 10% w/v (1.040) non-hopped wort leads to cells reproducing during propagation that will be culled under actual brewing conditions. Serial repitching results in culture that is tailored to one’s brew house because it separates the wheat from the chaff cell-wise.