I am pretty sure I know the answer to this, but I am just curious if anything OTHER than water boil off changes the gravity of the wort during the boil period.
I brewed an IPA the other day, target OG was 1.067 @75% eff. I got exactly 5 gal 1.070 wort after mashing/sparging. My target batch size is 5 gal, but I knew that after I boiled, my OG would increase due to water boil-off. So I added water about half way through the boil to increase the volume to 5 gal by the time th boil was complete, which is the volume I got into the fermentor.
So, my question is: Did I still have a 1.070 OG beer of 5 gal after boil because the volume is still 5 gallons?
This all stems from the fact that I forgot to take the OG reading after the boil, so I really do not know if it was 1.070 or not.