3rd partigyle help...how to cap an Imperial Stout mash

[SethMasterFlex]

I'm attempting my 3rd partigyle brew. The first two were a barleywine/IPA and a barleywine/ordinary bitter combo. I know what I'm doing in the way of technique, but I dont know how to cap the mash for something that has dark grains in It already. My base recipe is as follows:

84.0% 2 Row
3.5% Flaked Barley
4.0% Special B
2.0% C120
3.0% Roasted Barley
2.0% Chocolate Malt
1.5% Black Patent Malt

Mash 150F for 60 mins
OG = 1.111 @58% efficiency

I'm going to be using my first runnings to make a 3.5 gallon batch. I want to make a mid level stout with the second runnings. I will obviously end up with a beer on the. How much if any crystal/dark grains/flaked barley will be left. How much roast barley/flaked barley/chocolate/crystal will I have to add achieve 5 gallons of a mid level stout. I'm not really looking for numbers based on gravity additions, just what I have to add to get flavor and body contribution.

 

[erikpete18]

Hey, realize this post is a little old, but did you ever figure out what the result was as far as the darker grains? I'm planning the same partigyle (RIS-stout) except I might toss some flaked oat and a little pale malt in after I pull off the first runnings, so it would be pretty easy to toss a little more dark malt in there as well.

 

[SethMasterFlex]

I decided against doing one for lack of keg space.