Hard time matching numbers

[LuisLozano13]

Hey! So I brewed up some 5gal batches of oatmeal stout and brown ale using Maris otter as base malt, using about 11 pounds of grain per batch and I'm having a hard time matching my numbers, basically for the two recipes I used 70% of Maris otter malt and i was supposed to get an OG of 1.060 for both but instead I'm having OG's of 1.040 for both of the recipes I've adjusted them with table sugar, both recipes were mashed for 45 min and mash out making a total of about 55 min of mashing iodine test shows that there was a full convention of starch to sugars, any ideas?

 

[ColoHox]

What was your crush like?

 

[rmyurick]

I would expect a little lower than 1.060, depending on what grains were in your grain bill.

How long did you mash? You can probably get higher #'s by mashing at 60 min to an hour, if yours was less than that.

Assuming it was a contnuous sparge, how long did you sparge/runoff? To get good efficiency, it's best to slow it down a bit so that it takes 45 min to an hour.

The other thing (besides the crush) is how accurate is the 11 lbs.

 

[RonPopeil]

Extraction efficiency can be improved with a finer crush. I generally don't worry. It's a diminishing returns situation. The more you extract in sugar, the more you extract in the rest of the crap that you don't want. That's why people don't run 5 sparges. Shoot for 70-80% efficiency as a homebrewer. Some pros go up to 85% to save money on grain. For us inefficiency should taste better.

 

[WoodlandBrew]

How about laughtering efficiency? What were your volumes of water in a wort out? Or maybe just your vessel sizes and number of sparges?

 

[LuisLozano13]

It was a single batch sparge, I forgot to mention, I brew the same recipe and my numbers matched almost perfect, the exact amount of grain was 11.2 lbs

 

[DurtyChemist]

Pre and post boil volumes?
I would mash 60 minutes as the mash conversion test is only a small sample of a much larger population and unless you stirred the mash very well to get a homogenous sample it could give you a false positive test result.

 

[StubbornBeagleBrewery]

It was a single batch sparge, I forgot to mention, I brew the same recipe and my numbers matched almost perfect, the exact amount of grain was 11.2 lbs

There's a ton of variables here. So you are saying you've brewed the same beer with the same processes (grain crush, water volumes, etc), and had different results? Mash PH can also affect conversion, are you using measuring PH? I'm in farm country & my municipal water varies greatly from one season to the next due to factors like farm runoff, so it's another variable I measure carefully from one batch to the next & try to control.