Refractometer Compensation

Some time back I purchased a refractometer which has ATC and reads SG as well. I was so disturbed by the discrepancy between my hydrometers (2) and the refrac that I quit using it almost immediately.

I decided to try and understand my initial observations so I read for about three days on this forum and the web...

Here's where I'm at.

The refrac has been correctly calibrated with distilled water. I have also prepared several sugar water samples of varying densities and have measured each with all three devices (2 hydros and 1 refrac). The two hydros track within the limits of what I can read and both correctly reflect 1.000 in distilled water. All tests are with 60 degree samples.

The refrac is consistently low (3-4 points) from about 1.040 to 1.090.

I also tested my most recent brewing session with all three devices at preboil and post boil. Samples were read at 60-62 degrees. I observed the same basic discrepancy, about 3-4 points low with the refrac.

I'm assuming if I use a correction factor (+4) with the refrac I can basically assume it's within reason to a hydro reading???

So if I apply this correction factor to future measurements, my question is this... Will different density of worts from different brew styles significantly effect this correction factor? I know there's some effect, I'm hoping it's small.

Thanks...

That should work. I have my refractometer "calibrated" with my hydrometer in Beersmith, with a correction factor of something like .061. I calibrated both, and then plugged in the numbers into Beersmith. That auto corrects for me.