Why such a difference from my Hydrometer and Refactometer

[brewmaster48]

Tested gravity after primary on my saison, Hydro read 1.029, Refact read 1.045
temp was 60deg. Re-calibrated hydro and refacto with distilled water, both were right on.Are Refacto's just good for OG before Fermentation?

 

[david_42]

Refactometers only measure sugar levels in water accurately, not water/alcohol mixes.

 

[Golddiggie]

Once fermentation has started, you have to adjust the refractometer readings since alcohol will skew the results. There's a spreadsheet available (do a search for "refractbeer.xls", hint: it's on the More Beer site) that helps you to figure this out. I used this just the other day to get the FG on a batch I kegged. I used the refractometer for the OG, then for the FG, entering both readings into the spreadsheet. It adjusted and gave me the actual FG reading. I just wish it didn't use brix for the readings. Luckily, my refractometer is in both SG and brix... Thanks to Bobby_M... :rockin:

 

[rawlus]

Refractometer can be used in post-ferment conditions but an adjustment must be made to account for alcohol. Online tools and brewing software can do this, there are spreadsheets which will help calculate this too.

 

[amandabab]

the hydro is right.
after alcohol is in the mix you have to pretend one of the contradictory conversion charts is accurate for the refractometer

 

[jcaudill]

Notoriously inaccurate. I would only use a hydrometer with temp correction and a relatively small range for more accurate readings.