Background: I made a czech pilsner lager over a month ago. Figured out on the forum that my pitching temperature of 60F was not the optimal method, and likely the reason this lager and the ones before had diacetyl levels that never cleaned up with a diacetyl rest and lagering.
So, I immediately went to the forum for advice, and besides learning that i should pitch my lager yeast under 50F, i also learned that krausening is a good way to scrub the diacetyl and other off flavors. I made a 1800ml starter using light pilsen DME, chilled to 46F and pitched a vial of WLP 800 (used a different yeast strain than my lager -that had WLP802). at high krausen, i pitched the starter into a 5-gal corny keg, and racked my lager on top of it. I purged before and after lager was added, and left it at 50F for a week.
Drew a sample today, and I'm thrilled to report that there isn't a hint of diacetyl smell or taste...and I'm very sensitive to diacetyl. I'm going to drop down to lagering temps again and let it go for 2-3 more weeks, but I'm looking forward to drinking this beer.
thanks to Kai and Denny for their advice - wish you were here to sample the success