How grain crush affect grain absorption rate?

[swimIan]

How does the gap of your mill affect grain absorption rates? I mill at .045 currently with .6 oz/oz grain Absorption. I’m looking to mill a bit finer to troubleshoot efficiency (first step). In my upcoming test, I’d like to have my predicted water volumes as close to the resulting actual values. I hope this rules out as many variables as possible and makes for less test batches.

 

[C-Rider]

Never did any testing, but at .o45 that seems kind of a big gap. I do small batches w/5-7 lbs of grain and use a blender to create flour and get eff around 80 percent

 

[JohnSand]

Not much I think. A given weight of grain should absorb the same amount of water regardless of crush, as long as it is crushed enough to fully saturate. The different size of the particles may leave more space between them for liquid, but I don't think it will matter much on homebrew scale.
I grind on a corona, previously in a blender. I have no hard data or even observations on the ratio of grind to absorption. I squeeze the gain bag and let it drip as much as possible.

 

[kh54s10]

I haven't changed my mill settings much but have double milled a few times. I also never measured water amounts nearly that carefully. But I did not notice any difference when double milled. I think any difference will be very minimal.

 

[RM-MN]

How does the gap of your mill affect grain absorption rates? I mill at .045 currently with .6 oz/oz grain Absorption. I’m looking to mill a bit finer to troubleshoot efficiency (first step). In my upcoming test, I’d like to have my predicted water volumes as close to the resulting actual values. I hope this rules out as many variables as possible and makes for less test batches.

I wouldn't stress too much on getting the volumes close. The volume retained by the grain can be changed quite a bit by squeezing, not squeezing, hanging to let drip, etc. Worry first about efficiency by milling the grain finer, much finer, and if your efficiency seems to improve, then worry about getting the volumes right. Even the process of boiling can be a variable in your system.