Mash was dry, used oatmeal, is that why?

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I brewed a stout today, and the mash was a bit dry. Usually by the end of my mashes I've got my grains under a 1" or so bed of water. Today I used oat flakes, which I haven't done in ages (the last time was before I knew at all what I was doing), and today the mash was a bit dry. Efficiency dropped of course as well.

I had a half pound of oat flakes, about 7% of my 7 lb grain bill, for a 3 gallon batch of beer. I calculated 1.29 qts. per pound of grain, where I'm usually around 1.35 or so. I know I had less water per pound, but not so much different than normal.

Wondering if more experienced brewers can tell me, pound for pound, do oat flakes soak up more water than grain? Maybe it was a combination of the 2 things?

In retrospect, that .06 qts / lb difference didn't sound like much, but could easily become .4 or more or gallons total. Eh I may have answered my own question asking it.

 

[day_trippr]

Seems like a sound conclusion

Your question made me curious enough to take one of my Beersmith neipa recipes, note the recommended strike and sparge volumes along with the volume to the fermenter, then replace each of the grains with oat flakes until the entire grist was flaked oats (of course that wouldn't work - this is an exercise ) Beersmith didn't care at all. Weight is weight, so the strike and sparge volumes never changed, nor did the volume to the fermentor.

That said I suspect there is a difference wrt mash water retention - flaked remains seem gummy to me where malted remains seem quite dry. But because we typically use comparatively small amounts of flaked grains vs base malts the difference usually gets lost in the noise of batch to batch variation....

Cheers!

 

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Thanks for the reply.

I'm using an Anvil Foundry, and have measured and compensate for the dead space underneath and around the sides of the "grain pipe". But - the shape is a tall cylinder and I'm using the 6.5 gallon version, and that .4 gallons is around an inch of height of just water, and certainly more (2", 3"?) when the grains are in it. Goes quickly.

Guess I'll stick to 1.35 qts / lb and higher in the future!

 

[odie]

It would help to know how much total water and grain were in the mash tun. How much wort made it to the kettle. BIAB or 3V system? It kinda sounds like a BIAB set up but I don't follow "brand names" so I have no clue what "anvil foundry" means. There are so many different ones out there these days.

I'm kinda assuming BIAB in your case so was it a full volume mash you were attempting or was there water held back for sparging?

I've use oats in beers and never had a "dry" mash. But I do full volume BIAB with a dead space below the bag/basket. Even on large grain bills it's still below water level. I recirc but even without that it's still below water level.

 

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Anvil is an electric brewer with a pipe inside. About 3/4 gallon dead space under the pipe and maybe another 1/4 around it. 3-1/4 gallons water, 7-3/8 lbs grain for mashing (but keep in mind the dead space). Held a gallon back for sparge.

I think I've figured out the issue. The oats may or not have held extra water compared to grain. But more importantly I ran a bit on the low qts / lb side, and adding to that I accounted for the dead space under the pipe but not the dead space around the sides. Altogether my water line ended up below the grains.

The 6.5 gallon Anvil isn't particularly big of course and so even getting things a half gallon off is kind of a big deal. I think the space around the side is what got me, and I'll account for it next time.

Thanks everyone.

 

[odie]

that's sounds kinda small. most of my full volume mashes are 7-7.5 gal of water plus grain. But my kettle is 15 gal.