Determining ABV after wine is made

[Rocky]

From time to time, I have seen posts asking if there is a way to determine the ABV of a wine without knowing the original SG. There is if one is so disposed to do the work and I will list the method here. This was developed by William Honeyman, BS, PhD and was published in The Art of Mking Wine by Stanley Anderson and Raymond Hull. (I have paraphrased and listed metric units as well as English units.)

1. Measure the SG of the finished wine. This will be SG1.
2. Measure out exactly one pint (or 500 ml) of the wine. This is the "Sample."
3. In an enameled or glass pan, boil the sample until it is exactly 1/2 its original volume, i.e. 1/2 pint (or 250 ml). What had been reduced in this process is some of the water and ALL of the alcohol, because alcohol boils at a lower temperature than water, about 173 degress F (78 degrees C) for alcohol vs. 212 degrees F (100 degrees C) for water.
4. Using distilled water make the sample back to the original volume, i.e. 1 pint (or 500 ml).
5. Cool the sample to the temperatrue for which your hydrometer is calibrated and measure the SG of the sample now. You should get a higher reading (now that all the alcohol is gone). This will be SG2.
6. Find the difference between the SG2 and SG1, which we will call the "spirit indication" and read the ABV from the following where the first number is the difference in SG (spirit indication) and the second is ABV:

1.5=1%, 2=1.3%, 3=2%, 4=2.7%, 5=3.4%, 6=4.1%, 7=4.9%, 8=5.6%, 9=6.4%, 10=7.2%, 11=8.0%, 12=8.8%, 13=9.7%, 14=10.5%, 15=11.4%, 16=12.3%, 17=13.2%, 18=14.1%, 19= 15.1%, 20=16%, 21=17%., 22=18%, 23=19%, 24=20%, 25=21%, 26=22%

 

[AlFulchino]

cool...did not know this, thanks for sharing

 

[Runningwolf]

Rocky that is very interesting. Out of curiosity have you tested this on a commercial bottle just to see how close it is. I wouldn't expect 100% accuracy but just being withing a percent or two would be awesome.

 

[Rocky]

Dan, I have never tried this but the author claims the method is "as accurate as the ebullioscope," a fairly expensive piece of equipment to measure ABV.

I might give it a try. My reluctance is squandering a pint of wine! In the interest of science, I might give it a shot.

 

[buddy]

I've used this technique several times and as best as I can see, it does work fairly well.
You don't need to use exactly one pint, you can use a lesser amount. What is essential is that the starting volume and the finish volume be exactly the same.
What I have done is make a mark on my hydrometer test jar that is high enough to freely float the hydrometer. Add your wine up to that mark without the hydrometer in the jar. Then follow the directions given.
When adding the water, take the level back to the same line (make sure the hydrometer is not present). You should decant this into another container several times to make sure everything is well mixed.
It is also critical that the boiled wine has cooled to room temperature in order to get an accurate reading.
The way this works is that by boiling the wine you lose all of the alcohol and also some of the water. The boiled off water is replaced by the water when you top up so there is no difference in the water quantity.
The boiled off alcohol is also replaced by water, this is where you get the difference between the two readings. The greater the alcohol percentage the greater the difference in the reading.

 

[Rocky]

Buddy, We can agree to disagree on this, but I am going to stand by the one pint or 500 ml that Dr. Honeyman recommends because his calculations were based on this amount and it is a reasonable 'critical mass' with which to work.

The only change I will make to my original posting is that the sample needs to be boiled down to about and not exactly half of the starting volume. Of course, 'exactly' would work, but it is not necessary and would make the procedure more difficult to apply.

For those trying this, I will add that distilled water is required because minerals and contaminates found in tap water could affect the results. Also, people may interpolate to get their result for ABV when "spirit indications" fall between the mainly integers shown in my original post.

 

[Arne]

I have known about this for quite some time. I believe Luc has this on his website, but not for sure that is where I have seen it. My biggest problem with it is I havn't talked myself into wasting the pint of wine, so have never tried it. By taking starting and ending s.g.'s we know fairly close what the ABV is. No waste and I know it has a kick. Lol, Arne.

 

[Rocky]

Arne, I agree if you have the starting and ending SGs, there is no need to do this. This method is mainly for when one does not know the starting SG.

 

[Arne]

I know, but after waiting all that time for wine to appear from the juice, I just have a hard time wasting the pint instead of drinkin it. lol, Arne.

 

[buddy]

Buddy, We can agree to disagree on this, but I am going to stand by the one pint or 500 ml that Dr. Honeyman recommends because his calculations were based on this amount and it is a reasonable 'critical mass' with which to work.

The only change I will make to my original posting is that the sample needs to be boiled down to about and not exactly half of the starting volume. Of course, 'exactly' would work, but it is not necessary and would make the procedure more difficult to apply.

For those trying this, I will add that distilled water is required because minerals and contaminates found in tap water could affect the results. Also, people may interpolate to get their result for ABV when "spirit indications" fall between the mainly integers shown in my original post.

Fair enough Rocky, if you feel comfortable using one pint please continue to do so but if you look at it logically our methods amount to the same thing. You are taking a sample that is perhaps three times larger than mine, boiling off three times more wine and then replacing that with three times more water.
Then you take one third of that sample and put it in the test jar to measure the sg.
If you were to take your initial sample from the test jar, you are boiling off proportionally the same amount of water/alcohol, the only difference is you will use 100% of the sample for testing.
As far as interpolating the numbers, I actually use the fermcalc chart to calculate the alcohol percentage so there is no interpolation required.
The added feature of the chart is that it will give you the percentage of solids in your wine. For me I don't know what the solid levels should be so this has no value for me.
To use the fermcalc chart go to this website. http://web2.airmail.net/sgross/fermcalc/fermcalc_applet.html
Select the alcohol tab and then the "boiling off method" tab.

 

[LJPelletier]

I wouldn't want to boil any wine away either. lol

 

[Sirs]

who would want to boil any away but if you've got a decent amount and your not sure of the ABV and you really want to know what it is, whats a bit boiled down gonna hurt even using a pint you can add it to something in the fermentation process and not really lose any