I'm going to be making an Imperial Stout soon, and I've been doing a 2 step mash, as per Gordon Strong's suggestion, just the base malts for most of the time (~40 min.), and then add the dark malts for the last 15 min. or so. I'm convinced this helps the dark malt flavors, thanks, Gordon.
I recently tested my water, and am using John Palmer's spread sheet for residual alkalinity and additions calculations. So my 1st mash is basically the same as for a light colored IPA, little acid added with those malts, but then I want the water to be right for the final beer, which would become much more acidic after the dark malts are added. Suggestions? Thanks,