Oginme
Grandmaster Brewer
I would guess that the other losses come with grain absorption.
The other thing to consider is your boil off rate and it may be worth setting up and doing a boil with just water measuring volume in and out to get a better handle on that figure.
Since you do not have reliable markings on your kettle, how did you measure the volume of water in? That may be another source of discrepancy in versus out.
I've met/heard of several brewers who mark their spoons. I have one spoon and several pots/kettles, so it was easier for me to make a series of custom dip sticks.
The other thing to consider is your boil off rate and it may be worth setting up and doing a boil with just water measuring volume in and out to get a better handle on that figure.
Since you do not have reliable markings on your kettle, how did you measure the volume of water in? That may be another source of discrepancy in versus out.
I've met/heard of several brewers who mark their spoons. I have one spoon and several pots/kettles, so it was easier for me to make a series of custom dip sticks.