July 5, 2010
Please Hammer, Don't Hurt 'Em
All-grain brewers worldwide are worried about increasing their efficiency. This is not, personally, something I worry about very much, but to some it's the holy grail. Or at least one of the holy grails. The first bit of advice you're likely to get when looking for tips on improving efficiency is to crush your grain finer. Frequently, the art of crushing grain seems to be in how closely to atomizing it you can get. I urge you, dear reader, not to go down this path. Experimenting with crushing grain into smaller and smaller particles can only lead to a micro black hole which will destroy the universe... or possibly a stuck sparge. And a stuck sparge is super annoying.
I can empathize with the urge to increase efficiency, and a poor crush can be problem. Contrary to popular belief, though, the real issue is not coarse crushing, but inconsistent crushing where some amount of malt passes through the mill without being cracked or crushed at all. Grinding everything into dust does guarantee that all the kernels are being crushed, but there is also the potential that crushing your malt into flour will decrease efficiency past a point due to wort absorption. It's not too hard to imagine that flour absorbs more liquid than crushed or cracked grain, and this can make a noticeable difference in efficiency. You can go too far when it comes to crushing grain. The ideal, in this writer's opinion, is to expose the interior of the malt to the mash, without completely destroying the grain itself.
The key is, crush your malt well. Make sure it's being crushed evenly and all or most of the kernels look cracked and uniform. Take a look at the grain as it comes out of the mill. Are the kernels cracked or broken up evenly and into uniform size? If so, give it a whirl. Take specific notes on collected volumes and gravity through out the process, and see where your efficiency lands. If there is no improvement, try crushing finer in increments. And hey, a few points in efficiency is probably worth not having to dump out your mash into another vessel because of a stuck sparge.