I am doing another brew today and was planning on repitching from a batch that’s ready for kegging. I usually pour the yeast cake into a clean carboy and transfer the chilled wort, or vise-versa. Can I just transfer onto the cake reusing the same fermenter? Seems there is’nt anything in there that will harm the new batch. What do you think?
Yes, done that before. Saves on cleaning and sanitizing too
If your first beer tastes okay and you were diligent in your sanitation when racking it, then there should be no problem. I’ve gone as many as 3 times with out a problem.
You might consider pouring off some of the slurry and saving it for later. Your new beer, if of the same gravity, really doesn’t need that much yeast and you can save it for later use. If you’re ramping up to a bigger beer, then use it all.
+1 The long answer to my lazy reply 
Makes sense, glad I’m not the only one who’s lazy but not stupid.
Oh no, I can be both if I put my mind to it…
Or if I don’t put my mind to it. ;D
But, I would say it isn’t best practice. A little extra effort is like insurance.
I don’t know about that. The recently emptied carboy is demonstrably free of contaimination. by transfering the yeast cake to another container you are exposing it to contaminated air far more than by leaving it where it is. but I don’t think it is much of a difference.
It’s only just okay practice to use just a portion of the yeast-cake. It is full of dying and pooped out yeast. This can and will certainly lead to off flavors in spite of an apparent vigorous fermentation.
Best practice would be to make a starter from a bit of the yeast and use a clean fermentation vessel. I don’t think “demonstrably free of contamination” can be assumed or demonstrated without the aid of a microscope. Yeast health is more of a concern at this point than contamination through transfer.
At some point cutting corners by repitching onto the cake and into a gunky fermenter will fail- such as resulting in a beer that falls inexplicably short of expectations. The brewer will then post on the AHA wanting someone to diagnose their off-flavored IPA/Imperial Stout/Ale etc. :
I’m not saying don’t do it- we are “homebrewers” after all. Just be prepared for problems at some point.
agreed. What i meant by demonstrably free of contaimination is that the beer coming out of the carboy has been tasted and appears to be free of contaimination related off flavours. Personally I have only repitched for 1 additional generation as my brewing schedule is not regular enough to continue to reuse the yeast and I am not confident enough in my own yeast handling to save it.
When I do it, its because I need the whole yeast cake for something big, and I only go from session beer to imperial, and/or mild to hoppy, because I dont want to risk carrying over more dominant flavors. I.E. I’ll go from Blonde Ale to Barleywine in the same carboy, but certainly I wont go the other way. If its session to session, I’ll portion it out in pint mason jars, and refrigerate the remain for other batches.
I think you guys were just looking for a reason to say “demonstrably” 
I would say it is demonstrably true that, at least in my case, I make an effort to find oportunites to use the word “demostrably” as often is is demostrably reasonable ;D
Ever notice demonstrably starts with [Church Dance] DEMON [\Church Dance]
Ok OK I get the point! I’ll make a starter. You guys are demonstrably nuts! But thanks for the good input-all points taken.
;D