Proof Vs %

[Squiggly]

I always thought proof was double the %. My father gave me a bottle of London Dock which reads 100 proof - 57.1% alc. Then a few months later he gave me an other bottle of London Dock that reads 70 proof - 40% alc. Does any one know why the difference.

[rumdog007]

I always thought proof was double the %. My father gave me a bottle of London Dock which reads 100 proof - 57.1% alc. Then a few months later he gave me an other bottle of London Dock that reads 70 proof - 40% alc. Does any one know why the difference.

You are correct for North America. However, bottlers in the UK adhere to the 7:4 system for their UK market labels.

[Squiggly]

These bottles were purchased in Canada (Winnipeg I think ?) The label says blended and bottled in Canada for White Favell (Vinters) London. Is it because it's a english company?

[Edward Hamilton]

It looks like this one got through the labeling process for Canada which uses alcohol content by volume as does the US and most of the rest of the world.

As mentioned above, British proof is calculated differently than US proof, which is twice the alcohol content and expressed as %abv.

It appears that the Canadian labeling authority was only concerned with the % alcohol by volume and not the proof statement.

[Paulipbartender]

British proof system is based on the alcoholic level required to cause an aggressive reaction if mixed with gunpowder and ignited. This would be seen as 'proof' that the liquid was of a certain alcoholic level in the days before hydrometers etc.

There are some other cool ways to test proof levels. Add oil to overproof rum and it will sink, but it will float in underproof. Or you can shake rums vigorously in a test-tube. An overproof rum will form tight bubbles that will disperse quickly, an underproof will form larger bubbles that disperse much slower.

[pkazimir]

yeah the gun-powder test. I think i read something about it in the Wayne Curtis book "and a bottle of rum" in the captain morgan & grog chapter. They also used gun powder as an ingredient in their drinks. heavy stuff...

I like the oil test will definitely try it ... just because of curiosity

[Paulipbartender]

It's a cool experiment - but a shocking waste of good rum!!!