refractometer vs alcoholmeter

[Denizh]

I accidentally broke my alcoholmeter halfway through my run yesterday and it got me wondering if I can buy a refractometer and use that to determine the alcohol content of a distilled spirit?

[zed255]

You need a specific refractometer for distilled spirits, a 'Spirit Refractometer'. They are readily available on Amazon and eBay, and I'm sure other sources.

They generally read from 0% to 80%, so for high ABV readings you will need to accurately dilute the sample. I use a small syringe to draw up my sample and water in equal amounts for anything I expect to be above 60%. Actual ABV of such a diluted sample will just be double the reading.

I love my refractometer, in particular for the devices ATC feature and small sample size. Fast and easy.

[PipeWelder316]

This makes me wonder. I use a refractometer to check the potential alcohol in beers, wines, whiskey mashes. In order to get a true reading one must use a hydrometer after fermentation or during depending on what your doing. my question is can the Spirit Refractometer be used inplace of the hydrometer? I realize its intended purpose is for spirits but if the scale ranges from 0-80% or would the sugars and other contents skew the reading?

[raketemensch]

You would want a separate Wort Refractometer. They’re very similarly priced, and outrageously useful. No more filling a full flask with wash/mash...

[zed255]

There is a conversion calculation for using a Brix /SG refractometer after fermentation has begun. Several sites offer online calculators. You just need to remember to get your OG as it is required data for the calculation.

[Rod]

You need a specific refractometer for distilled spirits, a 'Spirit Refractometer'. They are readily available on Amazon and eBay, and I'm sure other sources.

They generally read from 0% to 80%, so for high ABV readings you will need to accurately dilute the sample. I use a small syringe to draw up my sample and water in equal amounts for anything I expect to be above 60%. Actual ABV of such a diluted sample will just be double the reading.

I love my refractometer, in particular for the devices ATC feature and small sample size. Fast and easy.

Can you please give me the ebay site

I am in Australia and would like the brand name , rather than re-invent the wheel

Rod

[zed255]

Can you please give me the ebay site

I am in Australia and would like the brand name , rather than re-invent the wheel

Rod

The cheaper ones are 'unbranded'. Mine correlates well with my traditional spirit hydrometer. You're looking for something like this:

https://www.ebay.com.au/itm/Mini-Refrac ... Sw6GJaTDmc

[Rod]

Can you please give me the ebay site

I am in Australia and would like the brand name , rather than re-invent the wheel

Rod

The cheaper ones are 'unbranded'. Mine correlates well with my traditional spirit hydrometer. You're looking for something like this:

https://www.ebay.com.au/itm/Mini-Refrac ... Sw6GJaTDmc

On it's way mate ,

be here from mid April till next month

[Birrofilo]

You need a specific refractometer for distilled spirits, a 'Spirit Refractometer'. They are readily available on Amazon and eBay, and I'm sure other sources.

They generally read from 0% to 80%, so for high ABV readings you will need to accurately dilute the sample. I use a small syringe to draw up my sample and water in equal amounts for anything I expect to be above 60%. Actual ABV of such a diluted sample will just be double the reading.

Although a specific Spirit Refractometer would be more comfortable to use, I do believe that any refractometer could theoretically be used, with the help of a decently detailed conversion table, which I am still looking for.

A refractometer reads the refractive index of some light which passes through a certain liquid.

As an example, when your wort refractometer shows you the wort is 16,8°B, what it is actually measuring is not the density in Brix. It measures that the liquid has a refractory index of, let's say, 1,35856 and that would correspond, in a mixture of only water and sugar, to the refractive index of a mixture of 16,8°B. The instrument - being a refractometre - only measures a refraction, but then outputs to the final user the datum he's interested in. If the instrument is an instrument for a winemaker, the information requested is 16,8°B. The winemaker is not interested in the fact that the liquid has a refraction index of 1,35856.

In a mixture of water and alcohol this refraction index of 1,35856 corresponds, let's say, to an ABV of 41,51%. A spirit refractometre would output 41,51% ABV in the assumption that the liquid is a mixture of water and alcohol.

I do believe that if you put your mixture of water and alcohol through your wort refractometer, and it tells you "16,8°B", with the help of a lookout table you can read "41,51% ABV".

What I don't have is a well-defined lookout table that would give me a correct ABV reading for each tenth of degree Brix.

Somewhere between 82% and 83% ABV the relation between refraction and ABV becomes inverted, so a reading of let's say 1,36370 IR would correspond either to circa 63% ABV or to circa ABV 93%.

The only values that I have found are those:

ABV - IR - °B circa
0,00 - 1,33316 - 0,1 or 0,2
7,61 - 1,33795 - 3,4 or 3,5
15,55 - 1,34362 - 7,2 or 7,3
24,42 - 1,34914 - 10,8 or 10,9
41,51 - 1,35856 - 16,8
60,45 - 1,36336 - 19,7
66,44 - 1,36410 - 20,2
71,23 - 1,36462 - 20,5
77,35 - 1,36476 - 20,6
82,86 - 1,36490 - 20,6 or 20,7
83,55 - 1,36486 - 20,6
92,68 - 1,36370 - 19,9 or 20,0
96,33 - 1,36237 - 19,1

"Or" means somewhere in between.

The Index of Refraction increases from 0% ABV (1,33316) to a maximum of 1,36490 (or very near that) which is at around 83% ABV, and then decreases again slightly until it becomes 1,36237 for 96,33% ABV.

What I would like to find is a more detailed lookup table which, for each tenth of degree Brix measured by the instrument, gives the value of alcohol content as % ABV.

Such a table would allow all of us to use our "Brix" refractometer as a spirit refractometer.

[MoonBreath]

Brewhaus sells premium alcoholmeters with 30-60%abv, and thermometer with correction tables..
Temperature corrected here.

correction-table-for-alcoholmeters-1.jpg

[zed255]

Although a specific Spirit Refractometer would be more comfortable to use, I do believe that any refractometer could theoretically be used, with the help of a decently detailed conversion table, which I am still looking for.

A refractometer reads the refractive index of some light which passes through a certain liquid.

...

What I would like to find is a more detailed lookup table which, for each tenth of degree Brix measured by the instrument, gives the value of alcohol content as % ABV.

Such a table would allow all of us to use our "Brix" refractometer as a spirit refractometer.

Yes, just for giggles I put a few different concentrations (ABV) of neutral onto my SG / Brix refractometer. It appears one could use a single device using a conversion table, up to about 80% ABV. Just over 80% ABV the relationship between ABV and refractive index reverses, which is most certainly why there are no refractometers capable of reading 100%.

Seems the easiest approach it to simply put a known ABV onto the SG / Brix refractometer and generate a table empirically. I suppose samples in 5% ABV increments would be alright, and values in between linearly interpolated. Minimal error and a reasonable set of samples.

[Birrofilo]

Seems the easiest approach it to simply put a known ABV onto the SG / Brix refractometer and generate a table empirically. I suppose samples in 5% ABV increments would be alright, and values in between linearly interpolated. Minimal error and a reasonable set of samples.

That would be very nice, but it would sum up the hydrometer error with the refractometer error.

Maybe the forum could start up a collaborative effort. People puts their observed lookup table with the method outlined by you, and post it in a thread.
The numbers will then be crunched into averages that, for a large number of participants, should make possible to write a precise lookup table, which could be used by distillers of the entire world, for good. A definite contribution of this forum to the Holy Cause of home distillation.

Such a lookup table must already exist somewhere in scientific literature though, but I could not find it (except the values which I quoted in my previous post).

Actually, supposing the refracting index of brown distillates is different than the one of "white" distillates, the forum might write two tables, one for white distillates (probably more precise) and a generic one for "brown" distillates (probably less precise as different brown distillates could have different RIs).

I would start the new thread myself but I "still" have to buy my first still (and also the first alcoholmeter), so at the moment I am not able to contribute any table to the thread.