Gravity questions

[Darth_Beer]

Posted this to the homebrew group on facebook, but thought I might get some help here as well...

I need some help understanding something.
Last month I made an amber recipe (8 pounds amber LME 1 pound CaraMunich II, 1 pound Dark Munich, 1.5 oz Cascade @60min, 3/4oz Cascade @ 10min) Mashed at 148 for 60min. OG was 1.062.

Last night I made the same recipe (though changed the hop bill a tad.. 1oz Cascade, 1/2 oz Willamette @60 min, 1/2 oz Willamette @ 10min) Mashed @150 for 60min, and measured a 1.103 OG.

Can the mash temp really affect my brew THAT much? Both gravity readings were taken from the boil kettle before topping off to 5.15 gallon in the fermenter. First batch was read @ 70, while the second batch was temp corrected @90. Just trying to understand the how, and why my readings for the mostly same recipe are that far apart.

Thanks, Tim

 

[Punx Clever]

How are you taking gravity measurements? Hydrometer?

Based on your fermentables, that would take (1.103) 3.25 gallons at 75% efficiency. Compared with 5 gallons at 75% to hit 1.062.

The only thing I can think of that would cause that difference is a different volume in your kettle at the end. 2 degrees in the mash isn't going to change your gravity that much... hell, the grains are only giving you ~10 gravity points to begin with.

 

[AnOldUR]

Just trying to understand the how, and why my readings for the mostly same recipe are that far apart.

Stratification. Stir better before taking sample.

The CaraMunich doesn't have to be mashed and the Dark Munich has a hard time converting by itself. There's no way you could get 1.103 from that recipe if your volumes are correct.

 

[Darth_Beer]

Thank you guys. That makes sense.