Originally Posted by FenoMeno
Will the refractometer read correctly after fermentation?
No, alcohol has a higher refractive index than water and a lower density.
So a finished beer might have a refract reading of about 6 (equivalent to 1.024),
but a hydrometer reading of 1.012.
There are calculators available in Beersmith and online to estimate the FG of a beer based on the OG and the final refract reading.