I have siphoned beers onto yeast cakes 2-3 times now and have had good success( always going from lighter to darker and bigger...) Anyway I have a nut brown ale that has been in primary for 3 weeks and I am going to put it into a bright tank for a few days before bottling. I want to reuse the S-04 yeast cake for another barleywine attempt, but this stuff was a VERY active fermentation. I mean to the point that you cannot see into the carboy from the crud left behind all the way up to the bung. Assuming my sanitation was good ( I believe it was) would there be any issue with the crud in the fermentor from the previous beer? I would think NO since it is the same stuff left in the trub but this was beyond anything I have seen so far. I guess I could Wash the yeast cake and pitch the entire thing , but is that a necessity ?