Determining ABV after the fact

[richmke]

Let's say you did not take an original SG measurement, or you are not sure which ABV conversion equation to use. And, the Vinometer is notoriously inaccurate.

It occurred to me that you can use a Refractometer and a Hydrometer to estimate ABV.

In theory, the refractometer is affected by alcohol level. the hydrometer gives you actual SG. Given the difference between the two, and knowing how the refractometer is affected by alcohol, you should be able to calculate a good estimate of actual ABV.

A calculator is available at:
http://www.northernbrewer.com/learn/resources/refractometer-calculator/

 

[salcoco]

there is a better method at the Valley Vintners web site under resources. Our wine club tested this method against a ebullameter (SP?) which is the official measurement tool required by the government. the use of hydrometer and refractometer was within 1% of the official methods.

 

[geek]

I guess is time for me to get a refractometer...
I could not measure SG on my recent batch of Chilean grapes, actually I hate taking a reading because of how thick the liquid is and for me a bit difficult to get the hydrometer to give me an accurate reading (sticks).

 

[GreginND]

Thanks for the information. The Valley Vintner's method looks pretty accurate. But using a hydrometer and refractometer would be much simpler and not waste as much wine. Does anyone know how accurate that is?

 

[salcoco]

see my previous post comparing results against a ebulliometer. finally got the spelling correct.

 

[Runningwolf]

I use the ebulliometer at home and work. Can you give a link to the Valley Vinter instructions? I thinking of a cash Still which I think is even more accurate.

 

[salcoco]

here is the pdf of the instructions at Valley Vintner site..

I thought a cash still measured acetic acid.

View attachment MeasuringAlcohol.pdf

 

[Runningwolf]

It does measure VA but it will also measure abv including sweet wine unlike an ebulliometer.

 

[sdelli]

Hmmm... I was just told by a chemist at the Winemakers conference that the refractometer calculates on sugar and once alcohol is created it becomes worthless...

 

[Runningwolf]

Hmmm... I was just told by a chemist at the Winemakers conference that the refractometer calculates on sugar and once alcohol is created it becomes worthless...

He is mostly correct. I think with the right spreadsheets they can compensate the differences.

It's always best to use the right tool for the right job, but with some ingenuity those in the know can get around that.

 

[sour_grapes]

Hmmm... I was just told by a chemist at the Winemakers conference that the refractometer calculates on sugar and once alcohol is created it becomes worthless...

Here is an explanation of the "way around it" that Dan alludes to: http://valleyvintner.com/Refrac_Hydro/Refract_Hydro.htm

 

[sdelli]

Yipes..... I think I will just break out the hydrometer and read it! lol

 

[Angelina]

Pretty cool! I could totally see myself converting to this method of measuring.