In the Homebrew Recipes forum I posted a recipe for my Dopplebock and made mention of not overnight mashing this particular beer. @pweis909 @hoptualBrew both had some questions about overnight mashing, and I didn't want to derail the recipe post onto the topic, so I thought I would answer it here instead. There are quite a few others who use this method here on the forum, this is just my method. There questions are quoted below and then my answers. I use a cooler for my mash. I mash at the same temps I normally would at a normal mash pH. I wrap the cooler in an electric blanket wrapped in a sleeping bag. I lose about 1*F per hour, and usually mash 9-10 hours total. I don't have a pH meter or strips so I don't know what the drop in pH is, but if I don't acidify the sparge water my beers have a flabby finish from too high a finishing pH (if I add acid to the beer in the glass it is no longer flabby). I know that it is a pH thing and not an overnight mash thing as I have had it on regular 60 minute mashed beers as well. I have never had any lactic present itself in any of the 18 beers (9 mashes) I have done with this method, which includes 2 Pilsners, both judged in BJCP comps, one that placed 3rd in category. With only 10 hours of time and above 130*F I've never had any issues. I have started to blanket the mash w/ CO2 before closing up just in case. I had one mash that I did a partigyle on, the second runnings beer was all GP with very low hopping, and 1056. When I burped I could get a faint aftertaste of sour mash gone bad, not disgusting, just a very low taste like my bad sour mash berliner from a few years ago. It didn't show up in the big beer, just the second runnings one, and only after a burp. I have mashed at 149*F-152*F with no sugar added and gotten very low FG beers. I have mashed at 160*F on a 1.112 Wee Heavy (the first runnings beer mentioned above), fermented with 1968 & 1056, and finished at 1.033. I went from around 76% extract efficiency to 86%, even a couple 90%. Makes life a lot easier, put the boys to bed on Friday night, dough in, wrap up, have a beer and watch TV with my wife for an hour or so, go to bed, wake up, fire up the sparge water, batch sparge for 10.5 gallons post boil, either partigyle, split boil, or single boil/split ferment, usually done by noon, 2 at the latest (partigyle). I had a Saturday where we had plans from 9:45-5 out of town, I mashed in the morning, left for the day, came back and finished in the evening (can be used during week too around work schedule).