FG increased.

[JLP]

Can anyone explain this? I checked my stout FG with a hydrometer directly in the bucket at 62 degrees and the beer was at 1.018. I then raised the temp to 70 and left it for 3 weeks. I just kegged the beer, and checked it with my ATC Refractometer. It is now at 1.043. I just confirmed my Refractometer calibration, and it is on point.

 

[doug293cz]

Refractometers do not read correctly in the presence of alcohol. There are calculators that will estimate your current SG given the current Brix reading and the OG. In your case, just believe the hydrometer.

Brew on

 

[JLP]

Thank you!

 

[myndflyte]

You can use your refractometer to measure final gravity but you have to do some additional calculations and it won't be as accurate as a hydrometer, but it'll get you close.

Zymurgy published this in the July/August 2017 issue. They go into a deep discussion how they got it but if you just want the equations, they are:

FG = -0.002349Bxi + 0.006276Bxf
ABW = 0.67062Bxi - 0.66091Bxf
ABV = (FG * ABW)/0.791

Bxi is brix initial and Bxf is brix final.