Revvy,Question...when drawing a pipette sample for preboil gravity, where it's come out of the mashtun @ around 150ish degrees, how long to you have to let the sample cool before dropping it onto the lens? You mentioned something about the refractometer temp adjusting...but will dropping hot wort on it damage it?
Therefore the temperature of the instrument itself is affects the accuracy of the brix measurement and not the sample temperature (as Bobby_M suggests will rapidly cool). In other words, don't leave it in the sun or out in the freezing weather or it will read funny. Keep it at room temperature and it will be fine.[Temperature compensated refractometers] are temperature compensated by means of a bi-metal strip that expands or contracts depending on the temperature of the instrument. This bi-metal strip moves the optics inside the instrument to adjust for temperature variations.
I'll do the same during my next brew session and will try to remember to report back...Deathbrewer: If you do a side-by-side, please keep us updated! I plant to brew tomorrow, and will do the same.
The seller on Ebay is GainexpressBobby, what make and model refractometer are you using? Where did you buy it?
Ok, I finally got this figured out in BeerSmith, thanks to Brad.
Under Tools > Refractometer > Fermenting Wort:
Input your Brix in the field, then your OG beneath it. That will give you your corrected FG
Sorry If everyone else knew this, but for some reason I made it much more difficult then it should have been...