How accurate are the ABV %ages on labels?

@Jules I was listening to a program on a local channel yesterday and it was about the lab of our provincial liquor board. One of the thing they mention is that they check the level of alcohol of each product (except for rare bottles, I suppose) and they do allow a margin of error for the Producer but they also add that if the difference is too big they will ask the Producer to change the label. While they were saying that, they where showing a bottle of wine with an ABV of 13.25% labelled at 12.5%. Unfortunately, they didn't mention what they tolerate; neither they say if the margin of error was the same for wine, beer and spirits. I wouldn't be surprise, myself, if the ABV on whisky could be off up to 2%. I doubt it can be higher than that. When you think about it, it would mean that two bottles with the same ABV on the label could have a ABV difference of 4%. But I guess that most spirits have an ABV very close to the ABV on the label, probably with less than 0.5%.

The mixture homogeneity is another question. Maybe a chemist in the community could explain why we do not find an obvious alcohol seperation from the water as we find on a cocktail that rest for a time. We all know that the first dram of a bottle is very different because the more volatile flavors are more present. Maybe there is also more alcohol in this first dram.

Alcohol and water are both polar molecules. They mix well together. In fact, there is a ratio of alcohol and water (I don't remember) at which it evaporates at the same rate and we learned a specific word for that in chemistry.

So in solution it is unlikely a sample from one part of the container will differ from another part.

Of course, that doesn't mean that they always evaporate at the same rate. We know that different conditions during maturation cause the ABV to go up or down.

The difference between ABV on the label and in the bottle would likely be due to the following:

1. Batch labelling that fails to update the ABV (I know the LCBO listing for A'Bunadh is based on one batch from a while back) - so, a labelling issue.

2. Possibly, I guess, a measure of the ABV before all the casks are married together - so, a logistical error.

3. Calibration error. The distillery put the actual reading on the label but the device of the purchasing lab was calibrated differently. So who is correct? your guess is as good as mine.

I would hope the ABVs on the label would be fairly close to what is in the bottle. I would hate to pay Ontario tax on 62% and be getting only 58%.

Found it - AZEOTROPE

Source of all info in this post:

imeldalee18.wordpress.com/2011/02/…

The combination of 95.63% ethanol and 4.37% water cannot be separated by simple distillation. Azeotropes boil either at higher or lower temp than both of the components.

Water boils at 100 degrees Celsius, Ethanol at 78.4 degrees, but the azeotrope boils at 78.2 degrees.

Since I have never tasted a whisky at 95.63% ABV, it's a moot point for whisky lovers...

@Nozinan One learns something new every day! And that is why Everclear which is banned in many states at its' highest strength is a max 95% ABV. I am also thinking that the ABV must be fairly close as taxes are likely assessed on that basis. Below is a wiki link to rectified spirits etc.

en.wikipedia.org/wiki/…

@Nozinan,...yes, that 95.63% ethanol/4.37% water co-boiling point is why pure reagent grade ethanol can only be achieved by expensive chemical processing and is not financially practical on an industrial scale.

@Jonesz but how does it taste?

I don't think I drink whisky for the taste of the alcohol primarily otherwise I would just drink Vodka

@Nozinan Thanks for the infos. In Québec, they used a spectograph to measure the ABV (among other things). I doubt any Producer would use such an equipment unless for their mass production. I believe the spectograph has to be well calibered to work properly, so I trust they have very accurate values of ABV.