Thanks for the data Tom, your results have me wondering if my adjustment factor for my hydrometer has changed. I haven't recalibrate it in about 8 months. I've got an alt finishing up and the brown I brewed last weekend fermented like crazy and should be done by the weekend. I'll recalibrate and run FG both ways this weekend and post my results.
Ok, I just finished up doing my FG testing. I recalibrated everything before I took my readings. Since I always have a lab wash bottle of Distilled water handy I check my refractometer every time I use it. It is sensitive to ambient temperatures. Also, while it is an ATC model, I always cool my sample down to at least 90F before taking a reading.
Batch 1 Dusseldorf Alt
OG 1.048/11.9 Brix (by refractometer only)
FG 1.011 by Hydrometer (1.01 at 69.4F corrected to 1.011)
FG 5.8 Brix calulating to 1.011FG using Sean's algortihms
Batch 2 Northern English Brown Ale
OG 1.046/11.4Brix (by refractometer only)
FG 1.012 by Hydrometer (1.011 at 69.5F corrected to 1.012)
FG 6 Brix calulating to 1.012 FG using Sean's algortihms
Most of the beers I brew are 1.045 to 1.065 OG and Sean's correction factors give me great results. At this point I am content with storing my hydrometer for use on high OG brews.
Thanks again Sean. I appreciate all the time and effort you put into your refractometer analysis!