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Refractometer measurement conversion

https://www.thebrewingnetwork.com/forum/viewtopic.php?f=19&t=27758

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Refractometer measurement conversion

Posted: Fri Mar 16, 2012 1:52 pm
by Fisher kel Tath
Anyone have a good calculator for converting Brix to SG that takes alcohol into account.

Brewed a Belgian Dubbel original gravity was around 16.1, currently reading after 2 weeks at 6.5.

http://www.musther.net/vinocalc.html#monitorferment

that says that my OG was ~1065, and my current gravity is 1001 which seems a little low...though the beer does taste that dry...

Using Wyeast 1388 fermented at 66 degrees for the first 4 days then ramped to 70 for the rest.

Re: Refractometer measurement conversion

Posted: Fri Mar 16, 2012 6:21 pm
by Mike_n_dax
I'll have to watch this thread because to mu understand the use of a refractometer is helpful before pitching yeast.. after that the yeast interfears with getting an accurate reading and you have to revert to using a Hydometer.

Re: Refractometer measurement conversion

Posted: Fri Mar 16, 2012 6:43 pm
by spiderwrangler
http://morebeer.com/learn_vids/vids_refract

Instructional video and an excel sheet that does the calculating for you.

Re: Refractometer measurement conversion

Posted: Fri Mar 16, 2012 6:57 pm
by Fisher kel Tath
Yea...my refractometer has to be off...cause...98% attenuation isn't possible....

Re: Refractometer measurement conversion

Posted: Sat Mar 17, 2012 6:54 am
by brewinhard
Fisher kel Tath wrote:Yea...my refractometer has to be off...cause...98% attenuation isn't possible....



Refractometers are not the best instruments to use after fermentation has begun. The alcohol produced throws off the readings and there are some pretty heavy-handed calculations needed to compute to even get close to an actual reading. Even after the calculations, I am not so sure how accurate your results will be.

You are better off taking a true hydrometer reading and adjusting for temperature. Refractometers are best to use pre-fermentation, during lautering (measuring runoff), and during the boil. You could use them during the fermentation, but really only to determine if your fermentation has completed (ie - the readings don't change over the course of several days).

Re: Refractometer measurement conversion

Posted: Sat Mar 17, 2012 9:33 am
by mordantly
i find that 32 brix (~1.130) has been a limiter in pre-grav testing, but that spreadsheet is pretty damn close for government work post ferment.

Re: Refractometer measurement conversion

Posted: Sat Mar 17, 2012 9:51 am
by anday6
I got a 'bottling' hydrometer a while back and couldn't be happier. The resolution is good enough to see a change of 1/2 a point so you know exactly when the beer is done. Nothing like having the right tool for the job.

Re: Refractometer measurement conversion

Posted: Sat Mar 17, 2012 3:52 pm
by sharkguy05
Just as brewinhard said refrac are for pre fermentation. While beersmith n other software has calculations for post fermentation. I will tell u from experience n experiment that it is not accurate. Use a hydrometer, its the only way to be correct

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