I am not sure there is much insight to provide. If you have a general question or are looking for clarity, I say check out the yeast and fermentation section. Yeast Harvesting thread. As simply put it is collecting the yeast that was used to ferment beer. There are many different ways to do it. Some collect the trub, or slurry left post fermentation, top cropping ale yeast that are in the krausen can be scooped out with a spoon and harvested into a mason jar or what have you. Then lager yeast can be gathered via a cone, or slurry. Washing said yeast is also another story, some people do it, some do not. I for one say it depends. To clarify, if you want to make a black lager (schwarzbier), a IPL, and a Pilsner you will need to make the pilsner first otherwise the hop matter from the IPL and the roast from the Schwarzbier will mess up your pils. Is that about as clear as mud or crystal?