Originally Posted by Edpietrzak
I just got a new atc tempature correcting refractometer with specific gravity. Callibrated to 1.000 sg with distilled water and took a reading of a cream ale that I am about to bottle. The sg 1.021. So I took a hydrometer reading to compare and that says 1.008. Am I doing something wrong?
Refractometers work great for unfermented wort/must but once alcohol is in the liquid, it changes the way the light refracts through it so you need to take a hydrometer reading after fermentation starts.
There are correction tables to help figure the probable finished SG using a refractometer, but I haven't found them all that accurate.