How do you explain that, Jon?
In my case, by reducing my dead space to basically zero. I took out the braid which I admit was extended further into the cooler by the bulkhead conversion I did. But just by pulling the bag over a small amount away from the drain, it puts a gentle pressure on the grain bed (without squeezing) that I couldn’t have done before.
I’m not certain. Whatever they carry at the hardware store. I’ve got two mash tuns, as I usually brew two batches at the same time. One of them always drains better than the other. They both have the same braid, I think.
So basically the increase isn’t from the bag itself, but from the new setup the bag allows you to have?
Mostly, but there is an ability (while figuring zero dead space) to drain the grain bed more completely than you could before - the bag tends to get sucked into the drain somewhat and they recommend to pull the bag away from the drain a couple inches to let it drain freely. Doing that gets a little more wort/sugar out by gently squeezing the grain bed . Regardless, I like it pretty well.
I guess what I’m getting at is that there are other ways to accomplish the same thing. The bag is one of them. But so is a good braid correctly configured. In the end, it’s whatever works.
For sure.
Some general disclaimers for stuff that I see all the time…
If step mashing improves your efficiency, then you weren’t getting good conversion. Check your mill gap, and mash pH. Likewise if you’re benefiting from a mash duration longer than an hour. Likewise if mashouts.
Batch sparging works via dilution, there’s a hard limit on efficiency due to the laws of physics. I just don’t see how it’s possible for a mashtun brewer that batch sparges to get more than the mid to high 80s. It’s just not possible for a 12 lb 1.050-1.060 5.5 gal brew, with no deadspace or mashtun losses other than grain absorption, to get that high without fly sparging or having a lower absorption rate than 0.125 gal/lb.
@Hoisierbrew, have you measured to see if your lifting the grain bag lowers your absorption rate at all?
If your changing your mash process, and want to see how it changes your efficiency, you should be looking exclusively at conversion efficiency, and not mash/brewhouse as that will vary with different recipes and sparging process. Conversion isolates those out, and just looks at how well your gelatinization, extraction, and conversion (ie the mash) went.
There’s no way to get a single brewhouse efficiency for every recipe. You can have a typical brewhouse, for a typical brew (11-13 lbs for example), but a session brew will always have a higher %, and a big 1.090 brew will always have a lower %. This is unavoidable.
- Brew on.
I’ve lowered my absorption number to .1 gal/lb (from
.12) to compensate. Volumes are spot on now.
Thought that might be the case 
Good explanation for your lauter efficiency increase.
I know this sounds crazy but, I’ve been able to get wort left in grain down to 0.015 gal./lb. by squeezing the bag and not worrying about clear wort. Hope the beer doesn’t taste harsh. 
Yup.
I don’t believe it. I’ve stood on my grain bag while placed on a stainless perforated colander and barely got lower than 0.07 gal/lb. Can you provide the measurements from this baffling experiment?
I probably screwed up the math. For a 3.5 gallon batch (4.6 in boil) of Irish Red I used 8.3 lbs. of grain. After mash and squeeze the wet grain weighed 9.4 lbs. Of course, the dry weight of the grain after sugar extraction would be less than 8.3 lbs. Maybe that’s the mistake?
My grain bed is much dryer at the end of lauter with the bag than without it. Plus, I think clean up is much quicker and easier. For me the benefits are worth the price.
Jon, are you no-sparge or batch-sparge? If the later do you pull the bag a couple inches for both?
Would need to know the total water volume used between strike and sparging.
Weighting the grain bag after squeezing doesn’t work very well, as it’ll vary with the gravity as well as the absorption rate, it’s a formula I haven’t seen derived or used before and while I’m sure it’s not all that difficult to derive, I don’t really care to.
Apparent grain absorption rate ~= (Volume_Used - Preboil_Volume + Mashtun_deadspace) / Lb_of_grain
Mostly no sparge right now, some beers get sparged. I gently pull the bag a couple inches away from the drain anytime I drain. Not so much to get more wort sugar (though it happens), just a functional, easier draining/lautering thing.
OK, that makes much more sense. That way I get (5.3 gal. - 4.75 gal. - 0) / 8.3 lb. = 0.066
That’s right there with your 0.07… Whew!