We are recently going over hydration standards and experiments for grain hydration and at first I fell into the same trap! it's not as truly intuitive of a calculation. for grain hydration you divide the weight of water by the total weight of wet grain (H20 lb / total wet grain lb.) so in that case above it would be 6/16 = 0.375 for grain hydration. Granted it's oats so the natural hydration is about 15%. 10x.85 = 8.5 lbs of starting dry grain.
Meaning you gained 7.5lbs of water, so the closer calculation would be 7.5/16 = 0.468 or roughly 47% hydration. In our trials a full 24h soak of oats went from 40lb to 80lb consistently, and then a 15 minute boil only raised us up to 82lbs so we just did the soak and then a sterilize or pasteurize and the grains have been performing great!
Replied on Scoop out 10 jars of Oats into the po...
20 Jun 12:32
Tyler https://docs.google.com/spreadsheets/d/1QCi1Ogrk_7nvyacLw1d_7360WSq3iCZfFJznBBQesSM/edit?usp=sharing
Here is a google sheet calculator I made for grain hydration. you can use it to calculate out the hydration percentage of grain, along with figuring out the natural hydration amount. Also if you ever want to try and predict or get an idea of how many dry grains are needed for a certain percentage hydration, there is a calculator as well.