I just got my refractometer, and once I have a brew day I'll be able to do the wort calibration, but I'd like to use it on some finished beers so I decided to calibrate it now. I got the distilled water and set the zero. My refractometer has ATC.
To get the brix correction factor I made a solution of distilled water and table sugar. The hydrometer measured it at 1.032 (70F) corrected to 1.033 (60F) and the refractometer came in at 7.7.
Entering this into beersmith gives me a brix correction factor of 0.9306.
I don't have any problem with that, sounds good, but then I pulled a sample of my kegged cream ale. I let it come to room temp and let the CO2 come out of solution. Hydrometer read it at 1.009 and the refractometer at 4.2. That gives me a calculated OG of 1.030. I am notoriously lax on my OG reading, but I thought it was more up at 1.044. That would be an all-time low efficiency (50%) by about 20%. That just doesn't seem right.
To get the brix correction factor I made a solution of distilled water and table sugar. The hydrometer measured it at 1.032 (70F) corrected to 1.033 (60F) and the refractometer came in at 7.7.
Entering this into beersmith gives me a brix correction factor of 0.9306.
I don't have any problem with that, sounds good, but then I pulled a sample of my kegged cream ale. I let it come to room temp and let the CO2 come out of solution. Hydrometer read it at 1.009 and the refractometer at 4.2. That gives me a calculated OG of 1.030. I am notoriously lax on my OG reading, but I thought it was more up at 1.044. That would be an all-time low efficiency (50%) by about 20%. That just doesn't seem right.