Double Mash BM

[Rhodesy]

I am going to brew a RIS on Friday providing my 3L starter ferments out. I plan to use approx 10KG of grain split over 2 mashes, the first of which will be 100% pale malt. What I was wondering is anyone who has experience of doing a double mash? I am expecting a lower efficiency and have plugged this in to be around 65% Brewhouse as opposed to my normal 72%ish.

My plan is

-Top up BM to 25L and mash in.
- Normal mash followed by a sparge of 5L which will take it just above 25L mark
- Mash the 2nd batch including the dark, oats and roasted malts.
- Sparge with a further 5L or to take my to around 31L

Am I missing anything obvious? I usually mash with full volume which is typically around 34L or thereabouts, this often leaves me around the 30/31L mark pre boil. My beersmith profile accommodates for all losses in the BM (not any FV) to get me at my target volume which is usually 21L.

I guess I am stuck as to whether I should sparge with more on the 1st batch of 100% pale malt and reserve some wort to add post mash or keep the sparring split between both batches? I will be mashing at 67c for both with a quick 5 min mashout at 76c on the 2nd batch before sparging.

Any advice appreciated

[Wiganbear]

I've done a couple of double mash recipes with my BM and you seem to have it all covered.

[IPA]

Any particular reason you are not mixing the grain evenly for the two mashes. Your normal efficiencies seem very low I usually achieve 85 plus.

[Rhodesy]

Any particular reason you are not mixing the grain evenly for the two mashes. Your normal efficiencies seem very low I usually achieve 85 plus.

The grains are already mixed as it was a custom made pack. One of the bags is 100% malt whilst the other has all others including of course more pale malt, both of which are around 5KG each. My mash efficiency typically ranges between 85-87% however I was referring to Brewhouse efficiency as its through that measure I adjust in beersmith. I also plug all losses as boiler and not FV losses which also affects this.

Due to this being a high gravity brew the general rule of the thumb is that efficiency will drop which I have looked to compensate as a result.

[woblylegs]

normski and i did a R.I.S and double mashed. worked a treat . you will be good to go with what you are doing.

[john luc]

How does doing a second mash effect PH in the wort of after the first mash.

[Rhodesy]

normski and i did a R.I.S and double mashed. worked a treat . you will be good to go with what you are doing.

Thanks, like many things it will be a bit trial and error but looking forward to doing something a bit different for this one.

[MTW]

Just something you said: you're hoping your 3L starter ferment out in time? You should be fine to chill it down once it's passed the max growth stage. From what I understand, letting it go right through only serves to place greater demands upon pitching. If time is tight, even more reason to get it chilling as soon as poss, especially if you're planning to decant before pitching.

[Rhodesy]

Just something you said: you're hoping your 3L starter ferment out in time? You should be fine to chill it down once it's passed the max growth stage. From what I understand, letting it go right through only serves to place greater demands upon pitching. If time is tight, even more reason to get it chilling as soon as poss, especially if you're planning to decant before pitching.

Yeah the Krausen has dropped so it is currently chilling down just now so hoping it will be fine to go ahead and brew tomorrow. I will be decanting prior to pitching.

[McMullan]

Which yeast strain are you using? How are you going to oxygenate the wort?

[IPA]

I have just looked up a RIS that I brewed just over a year ago. It is a recipe by Graham Wheeler and was fermented with the yeast I revived from a 1983 bottle of Courage Russian Stout.

Final volume 20 litres

5320 gr Pale malt
1750 gr Amber malt
340 gr Black malt
820 gr White sugar

100 gr Challenger 7 percent alpha 90 mins

OG 1.098
FG 1.014
Bitterness. 56 EBU
Colour. 222 EBC
ABV. 11.35

Double mash in BM

[Rhodesy]

Which yeast strain are you using? How are you going to oxygenate the wort?

Using a clean strain for this attempt being WLP090 as it attenuates well. I don't have pure oxygen so will be using an aeration paddle attached to a drill to assist, not ideal but hopefully won't be too detrimental.

[Rhodesy]

I have just looked up a RIS that I brewed just over a year ago. It is a recipe by Graham Wheeler and was fermented with the yeast I revived from a 1983 bottle of Courage Russian Stout.

Final volume 20 litres

5320 gr Pale malt
1750 gr Amber malt
340 gr Black malt
820 gr White sugar

100 gr Challenger 7 percent alpha 90 mins

OG 1.098
FG 1.014
Bitterness. 56 EBU
Colour. 222 EBC
ABV. 11.35

Double mash in BM

Thats impressive attenuation, I recall reading the thread where you mentioned recovering the yeast.

[john luc]

I have just looked up a RIS that I brewed just over a year ago. It is a recipe by Graham Wheeler and was fermented with the yeast I revived from a 1983 bottle of Courage Russian Stout.

Final volume 20 litres

5320 gr Pale malt
1750 gr Amber malt
340 gr Black malt
820 gr White sugar

100 gr Challenger 7 percent alpha 90 mins

OG 1.098
FG 1.014
Bitterness. 56 EBU
Colour. 222 EBC
ABV. 11.35

Double mash in BM

Thats impressive attenuation, I recall reading the thread where you mentioned recovering the yeast.

What's your verdict on the final beer.

[IPA]

It tastes exactly like the original. Having said that the beer is unlike any other that I have tried and you will love it or hate it. Not one for the Lager Boys