% ABV seems a bit strange - Help?

by **lyonacre** » Sun May 15, 2011 8:45 pm

Hey,
Last year as the sloes were coving the world we decided to make some sloe gin.
Followed the \"recipe\" that the Plymouth Gin Distillery talks about on their tours in terms of not adding any sugar but soaking the sloes in strong spirit - 76 ABV - and then cutting it back once the sloes have \"infused\".
Did that, all went well - the taste is terrific BUT it takes the top of your head off, I assumed because it is 77%.
When I check it with the spirit hydrometer it is nothing like 76%, more like 30!
What am I missing?

by **MrCat** » Sun May 15, 2011 9:11 pm

As soon as you add anything apart from water to the spirit you render a hydrometer useles as you don't know what it will do to the reading

An Alcometer (as apposed to a Wash, Wine & Beer Hydrometer) is used to test the strength of your spirit. Additives such as flavouring and Liquid Glucose will distort the hydrometer readings. Alcometers should only be used to test spirit in the following conditions: before any additives such as flavouring or liquid glucose are mixed.

You might be able to try a flame test though as the spirit should still burn. If you take a small sample and add water until it won't light you should be able to calculate the original ABV (by knowing how much water you added.)

by **lyonacre** » Mon May 16, 2011 6:12 pm

Thanks for that.
Is it reasonably safe to assume it will be pretty similar to the starting strength?

by **goinbroke2** » Tue May 17, 2011 1:08 am

As MrCat said, an alcometer only works with water/alcohol.

If you take 75% alcohol and add grapefruit juice the hydrometer might go to 40% because all your doing is messing with the specific gravity. Specific gravity is effected by more than just water or alcohol.
In drag racing we must do a hydrometer test to prove we haven\'t been tipping anything into the gas. Same principal. No matter what you add to a liquid the SG will vary by percentage and type of liquid.

by **MrCat** » Tue May 17, 2011 3:22 am

Is it reasonably safe to assume it will be pretty similar to the starting strength?

If it\'s biting back at you then probably. I\'d take a teaspoon of it and try to light it. If it burns immediately you know it\'s over 57%.
I have a small (20ml) measuring cylinder I use for mixing essences which is very accurate so I\'d take 2ml of spirit and 1ml of water and see if it still lights, then try again with more or less water until adding a small amount of water means it won\'t light. As long as you know how much spirit there is and how much water you added to stop it lighting you can work out the orginal ABV.

by **phlogiston** » Wed May 18, 2011 3:25 pm

The only reason the ABV may have changed is if the high strength alcohol has extracted water from the fruit. It won\'t be very much, and it\'s likely that your sloe gin is about 70%. If you dilute it with half the amount of water, you\'ll still have something over 40%.