Pitching onto a yeast cake

On Friday, I made a 1.057 OG pale ale, around 55 IBU, not too many flameout hops. This Saturday, I’m brewing a big imperial stout, 10 gallons. I am strongly considering pitching half the wort (5 gallons) onto one of the pale ale yeast cakes. I’ve never done this before, and was curious if anyone has any pointers.

A couple of notes. I’m not going to rinse or wash the yeast in any way before adding the imperial stout wort. I plan to a oxygenate a little after adding the wort.

A couple questions. When should I rack the pale ale off? The night before? I don’t want to be inside racking beer with a book going outside, so I can’t do it right before. I could probably rack as late as the end of my sparge, so about 90 minutes before I pitch onto the cake. Would that be best? It would be much easier to rack the beer the night before so I have less to worry about on brew day.

Any other pointers or advice?

Why not rack as you are chilling? Even if you have a plate chiller you could ko into the kettle then transfer. Or just kill the boil, do a wp, and transfer while it’s standing.

Do it. I’ve done it several times with good success. Always immediately before though, so not sure about how long you can go, I usually rack off before I start brewing and it’s totally fine.

Go directly to a blow off tube. You’ll have vigorous activity within a few hours.

Originally posted by CLevar
Why not rack as you are chilling? Even if you have a plate chiller you could ko into the kettle then transfer. Or just kill the boil, do a wp, and transfer while it’s standing.

Originally posted by SpringsLicker
Go directly to a blow off tube. You’ll have vigorous activity within a few hours.

I have done this plenty of times, and I usually rack during mashing which I find is less stressfull.

Another thing to consider is that you have more yeast cells compared to the previous batch, a factor of 4-6 is a number I have seen. For a big beer you might be fine with this, but I usually remove half of the yeast cake right before adding new wort.

Anyway, I have always had vigorous and sucessful fermentations using this method, so I tend to ignore experts claiming this is "bad practice".

Racked off the beer durin the mash. Pitched directly onto the yeast cake for half (5 gal) and other half got fresh yeast. Fresh yeast (left) started bubbling first. However, the yeast cake (right) was obviously more active overnight. I’ve never lost a gallon to blow off before.

What is this, a carboy and blowoff bucket for ants?

Skip the tube all together next time, just a loose cover of tinfoil, CO2 coming out of the carboy will prevent any nasties from getting in.