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**jwalk4** · 10-06-2012, 04:09 PM

I know that double crushing your grains - that is to say, milling the grains twice - is said to yield a greater brew-house efficiency. But what kind of efficiency do you get if you only mill it once?

50% ? 60% ? 70% ?

Anyone out there only do one crush?

zakleeright · 10-06-2012, 07:27 PM

My understanding is that it is not good to over-mill your grain. I've always just run it through the mill one time, and get 80% efficiency if I'm doing a 6-gallon batch, and over 85% if I'm doing 15 gallons or more. The efficiency goes up on my system with larger batches, for some reason...I suspect mash tun dimensions.

Anyway, it seems I get good mash results from keeping temp constant/accurate, having the right grain/water ratio, ensuring no dry spots/clumps in grain (add grains to mash water slowly, good initial stir), and doing a good sparge. For a batch sparge, I drain the first runnings, then use 169F water and let it sit for 20 minutes, then drain that.
I got a bit better efficiency when I started using a march pump to continuously recirc the mash water, so there's a constant flow through the grain bed.
IMO, I would not double-crush the grain. Seems like over-crushing has the potential for a 'stuck mash', which is far worse than a couple points of efficiency you might get.
Cheers

**thughes** · 10-06-2012, 07:33 PM

No worries about a stuck mash with BIAB.

That being said, I have found that there is no appreciable difference in efficiency between a fine single crush and a standard double crush. I am a BIAB'er and this opinion comes from several experiments with different crushes over the course of the past few years, not hearsay or repeating second-hand "facts" (no offense intended to zakleeright). I currently use a corona mill and tear those little grains up pretty good with it.....get a consistent 83-83%.

ArcLight · 10-06-2012, 07:38 PM

>>That being said, I have found that there is no appreciable difference in efficiency between a fine single crush and a standard double crush.

I agree. But I think the concern is one doesn't always get a "fine" single crush, thus the suggestion to double crush.

The only danger of over crushing is you may end with more dust flowing out of the bag, into the wort, and becoming trub.

**thughes** · 10-06-2012, 07:56 PM

Agreed, especially if you are at the mercy of someone else to crush your grain. I do all my own crushing and have experimented with both single and double crush, fine vs course crush, and roller vs corona.

**jwalk4** · 10-07-2012, 12:00 PM

Ah, ok. Thanks for the input guys. I guess I'll have to brew more and find out for myself. Darn!

I had read a few threads on here advocating the double crush, but when I phoned up my LHBS they had no idea what I was talking about. Or, they did know what I was talking about, and played dumb so they didn't have to clog up their mill.

signpost · 10-07-2012, 12:41 PM

I recently got 77% efficiency from my first all-grain attempt. The grains were crushed (I assume single crushed) by Northern Brewer and I did it as a BIAB with sparge. It didn't seem to be an excessively fine crush.

Ettels4 · 10-20-2012, 08:56 PM

I am consistently getting 83-85% eff. with BIAB using Northern Brewer's standard crush. My setup is a 44q. Bayou Classic w/ the strainer basket and a 5 gallon paint strainer bag. I don't sparge but I do mashout at 170 for 10 min. and give a firm squeeze by pushing down w/ a pot lid on top of the grains several times. I lose .05 gal/pound of grain. I have to recalculate recipes based on this efficiency and end up using a fair bit less base grain. Hooray I saved a few bucks on base malts... but really I am wondering... am I losing some flavor too by using less base malt? Does anybody know? Whats the downside to this increased efficiency?

D_Nyholm · 10-20-2012, 11:15 PM

I was using Austin homebrew standard crush and got about 70% efficiency pretty consistently. I bought a monster mill and started crushing my grain myself and set the gap to just allow a credit card AND the numbers to fit through. Even with it set that far apart, I got a very fine crush and dust. On the two batches I did with that, I got 80% efficiency but almost a gallon worth of trub. I am going to try to crush the grain much slower thinking that the drill we used just spun to fast and tore up the grain instead of just crushing it.

**unionrdr** · 10-21-2012, 03:23 PM

The crush in my midwest kit looked more like cracks in the hulls to me. So I took an old mini food processor & pulsed 1/2C 3 times,3-4 seconds per pulse. chunky grit like consistency. Maybe less pulsing till tax time sees a grain mill. No corona mills localy??