Predicting OG before boil off

[jcarson83]

Does anyone take gravity readings of their individual batch sparges and then try and predict what the OG will be after the boil off? I've been doing this with sporadic results. I take a gravity reading from the 3 runnings (in the middle), correct for temperature, and then weight it based on the volume of each run off. I then correct for the lost water during boil off. I'll give more details if anyone is interested.

The reason I'm doing this is so if my efficiency is low for the recipe I can add some LME to make up the difference before I boil.

 

[Blender]

I take a gravity reading of the entire preboil volume to determine initial efficiency of the mash.

 

[BierMuncher]

...The reason I'm doing this is so if my efficiency is low for the recipe I can add some LME to make up the difference before I boil.

LME can be added with as little as 5-10 minutes left in the boil. Why not just do your boil, then take a sample and cool it when you're nearing the end, then dump in some LME if necessary?

 

[jcarson83]

I thought the gravity effected the IBU.

 

[Gabe]

You can get an idea by taking the gravity reading and x it by your pre boil volume then divide by your finished vol. ie: (1.040 SG= 40 GU x 13 gal pre boil divided by a finished vol of 10 gal =1.052-53. Should get you in the neighborhood. Good luck, Gabe

 

[WBC]

Look at it this way. If you get a less efficient sparge then that is the beer Gods punishment for not doing a good job sparging and a good incentive for doing better next time. If you cheat then you are not going to figure out what you are doing wrong because your concience tells you no big deal. There is no reason to not hit 75 to 80% every time if you watch every detail of mashing. It's just not that hard.

 

[jcarson83]

You can get an idea by taking the gravity reading and x it by your pre boil volume then divide by your finished vol. ie: (1.040 SG= 40 GU x 13 gal pre boil divided by a finished vol of 10 gal =1.052-53. Should get you in the neighborhood. Good luck, Gabe

Thats what I'm doing. Doesn't work.