Is there a way to determine gravity of the sparge?
My plan, & I will do this twice to collect the desired volumes.
mash 12# grain with 3 gallon H20.
Collect the first runnings in one bucket and then collect the sparge
in a seperate bucket.
I should then have approx 5 gallons of high grav and about 6 gallons
low gravity liquor.

how do I predict gravity / volume before and after boils?
If I'm shooting for OG 1.05, and my 6 gallons are say 1.045, how much
should I expect to collect in order to get 1.05.
Are there formula for this?

TIA

~Matt