I have a nice new automatic temperature compensation refractometer, and I've been excited to get more control over my process by measuring the original gravity at the start of the boil. Today I made my American Stout (my Christmas stout, nothing christmassy about it except when I brew it), with a 1.068 OG on paper. I was stoked when my refractometer told me I had a 1.064 OG at the start of the boil, thinking that I'd evaporate some water in the boil and hit my OG exactly. I was very not stoked when my FG was 1.050 after the boil. (I blew my mash temp, but that's a different story.)
I don't understand what happened. I put a few drops of 150 degree wort on the refractometer, waited for a few minutes for those few drops to cool, then took my reading. What did I do wrong? This is the second beer in a row where this has happened to me.
