Why are my refractometer and hydrometer so far off?

[AleJoe]

Just taking FG readings on my pale ale. My hydrometer is reading about 1.004 (temp corrected to 1.005) and my refractometer is reading 1.019. The hydrometer is reading about .003 low when tested in distilled water but thats still leaving me a spread of .01?

 

[Clonefarmer]

Just taking FG readings on my pale ale. My hydrometer is reading about 1.004 (temp corrected to 1.005) and my refractometer is reading 1.019. The hydrometer is reading about .003 low when tested in distilled water but thats still leaving me a spread of .01?

Refractometers read differently after fermentation. I think it has something to do with the alcohol, but I don't know the exact science behind it.

 

[Gregscsu]

Refractometers read differently after fermentation. I think it has something to do with the alcohol, but I don't know the exact science behind it.

This is exactly correct, due to the alcohol content in the beer it skews the refraction of the light through the refractometer. They due have correction charts for refractometers just for this purpose.

For the time being, use your temp and calibration corrected hydrometer reading to measure your FG until you get a correction chart for you refractometer.

 

[AleJoe]

very interesting, thanks guys!

I thought that Beersmith might have the correction chart but if I'm reading it right it is using a refractometer for OG and a hydrometer for FG

 

[Snausages01]

This might help:

http://onebeer.net/refractometer.shtml

 

[DirtyPolock]

Morebeer has an excel sheet that helps with the correction factor. You may want to check out the following link:

http://morebeer.com/learn_vids/vids_refract

 

[skiwithg]

very interesting, thanks guys!

I thought that Beersmith might have the correction chart but if I'm reading it right it is using a refractometer for OG and a hydrometer for FG

Beersmith does have a refractometer tool. You need to enter the OG in specific gravity, so you can take OG with a refractometer and convert to brix. Then enter current refrac reading in Brix with the calculation type set to "fermenting wort gravity". The corrected gravity field will show the SG after accoutning for alcohol.

Works great for me.

Cheers,
Glenn

 

[Yambor44]

Morebeer has an excel sheet that helps with the correction factor. You may want to check out the following link:

http://morebeer.com/learn_vids/vids_refract

Unless they changed that sheet, it was slightly off at one time. I don't use it anymore. I like that the other link from more beer.

Here are some nice calculators as well.

http://www.brewheads.com/calc.php