Cask Strength, Proof and Percent.

When looking at different Whisky bottles we see a few different terms on the label: Cask Strength, Proof and Percent are just 3 of these terms.  What do they mean?

Cask Strength: Refers to a whisky that is bottled at the strength at which it comes out of the cask.  Nothing is added or taken away.  Most whiskies are diluted with water to bring them down to a standard percentage of alcohol by volume, or proof.  The best way to enjoy a higher-proof whisky is with distilled or spring water.  This is how many distillers drink it.  You can add water to your whisky by adding room temperature water or an ice cube or two which ever you prefer.  Just be mindful that you do not over dilute your whisky.  Add water little by little, tasting the whisky after each addition to find the level you prefer. 

Proof: Is defined as twice the alcohol (ethanol) content by volume.  As an example, a whisky with 50% alcohol is 100 proof whisky.  In the 16th century a method of testing a liquor’s alcohol was the “gunpowder method.”  Gunpowder was soaked in a spirit, if the gunpowder could still burn the spirit was rated above proof.  This test was based on the fact that potassium nitrate is more soluble in water than in alcohol.  This method is not always 100% accurate as different grain sizes in the gun powder would dissolve differently.  The use of proof as a measure of alcohol content is mostly historical.  Liquor is sold by alcohol content as a percentage of alcohol by volume.

Percent: Alcohol by volume abbreviated as ABV or alc/vol.  This volume percent is determined by the number of millilitres of pure ethanol present in 100 ml of solution at 20 degree Celsius. (68 degree F).  This ABV standard is used worldwide as a standard measurement for alcoholic beverages.  There are even a few non-alcohol/low-alcohol beverages that have a ABV because of natural occurring fermentation but these are low enough that they are not considered alcoholic by nature. 

Sources:

https://en.wikipedia.org/wiki/Cask_strength

https://en.wikipedia.org/wiki/Alcohol_proof

https://en.wikipedia.org/wiki/Alcohol_by_volume