Specialty grain %'s when increasing base malt

Hi all, let’s say I am using a recipe posted online, but I need to add 4-5 lbs of base malt to make up for my lower efficiency. Do I need to increase the specialty grains by the same pro-rated amount to keep the grain %'s the same, or is this irrelevant?

For example: an imperial stout

20lbs maris otter
2lbs chocolate malt
1lb crystal 60
1.5lbs roasted barley

But I need approx 26lbs maris otter to achieve the same OG. Do I increase the chocolate malt/c60 and roasted barley by the same amount or keep as is? I always wondered this. Thanks!

This is a topic of some debate.  I’ll tell you that I increase all the grain to keep the relative % the same.  But not everyone does.

I increase amounts of everything to try to maintain the same percents.  It’s the only thing that makes sense.  Because, science.

^^^^
Yeah, science!  And, what is a recipe but a formula, a proportionate list of ingredients?  Your efficiency will vary equally across the whole grain bill.

The reason I can think of to just up the base malts is if extraction of speciality malt flavors somehow differs from the extraction of base malt gravity points.  I can imagine separating the speciality malts and steeping them in the wort instead of putting them in the mash (doesn’t Gordon Strong advocate for this?) in which case I would guess that the extraction of the flavors is not dependent on the wort gravity.  If the speciality malts are in the mash itself, then perhaps those flavors get extracted at the same rate as fermentable sugars.

How’s that for a scientific hypothesis?  I’m looking at you experimental brewers!

It depends. Scaling everything works well until you brew a big roasty stout and need to adjust for a wide difference in efficiency. You’ll also notice in the color.

Separating the two sounds unnecessarily complicated.  And a whole new can of worms trying to get the original balance of flavors, with two different, and as yet unknown, rates of extraction!  Assuming that the biggest variable is LAUTERING efficiency and not something to do with conversion in the mash, keeping the % makes sense.

Why would the extraction of nase malts differ from specialty malts?  Can’t think of a reason and I’ve never seen it happen.

Changing the ratios and/or amounts of ingredients in recipes always makes a difference.  You’re either diluting or concentrating the various ingredients if the ratios aren’t maintained.

+1 to adjusting ALL %'s of all malts used in a given recipe based on your efficiency.

I kind of suspect that the reason there’s any debate on this at all goes back into collective homebrew memory:  Somebody would buy an all-grain kit, fail to hit the expected OG.  LHBS would say “next time throw in an extra pound of base malt.”  Because that was about all you could do in that situation.

I’ll go against the grain; I don’t think it always makes sense to keep the relative percentages the same.

Can you elaborate?

I’m with you too.

Simple example
90/10 - 2row/c40 - 1.050 OG
80% efficiency 7.1 SRM
60% efficiency 8.6 SRM

Small, but that is a difference.

How much of that comes just from increasing the pale malt?

About 1/3 of the increase if only the pale is adjusted. This is just a simple example. Other recipes could be affected more.

What I’m saying is scaling isn’t perfect. There may be some adjustments needed. No matter how the recipe is communicated, knowing the efficiency is helpful.

Good example there. So in that scenario, would almost be best to increase base malt for efficiency, and color adjust with crystal?

Please enlighten.  I had indicated my belief that lautering efficiency being the issue, it should scale equally across the whole grain bill.  I don’t understand how this would not be the case.  Intuitively I’d think you are leaving more or less extract behind, but the composition of what you get out would be the same.  Scratching my head, awaiting help.

There is no right answer here.

I’m not an expert in chemistry or fluid dynamics. My numbers are based on the commonly accepted formulas. With roasted and specialty grains sugar extraction is secondary to color and flavor. Yes, some sugars come along as well, they are just secondary here.