Jump to content

Proofing Issues

John Bassett

Recommended Posts


We are a brand new distillery.  I am doing my first proofing test on a very small batch of moonshine.   I followed everyone's advice, using AlcoDens for my calculations and blended by weight.   I added the amount of water specified by the weight calculations, but my scale is only accurate to .5 lbs, making it a little tough for me to get accurate.  We'll bought a new scale for processing,  that is more accurate, but it won't be here for a few weeks.

I was targeting 95proof.   Once everything was blended, I was at 95.6 proof on my first measurement, 95.72 on my second measurement and 95.68 on my 3rd measurement.   All was going well and I had about 190 lbs of fluid at 95.6 proof.    I added 750ml of water (1.65lbs) , knowing that I am now chasing my tail.    I closed up the tank and agitated it for several minutes.     I let the tank settle for 15 minutes then took a measurement.   It was now reading 94.3 proof.

Ok, I overshot, but have plenty extra to mix.   My question is not about how much to add.  I have the calculator for that (I miscalculated).   My question is:    How long does it normally take for the added water to get fully blended into the mixture?



Link to comment
Share on other sites

It would seem that your blending targeted at 95 proof was actually spot on (and not 95.6) because if you calculate 190 lb of 95 proof plus 1.65 lb of water you get 94.25 proof.  I would guess that everything was correct, but your gauging after the first blend gave a slightly higher reading than it should have.

Others have also mentioned that immediately after blending the measured proof can be slightly high and the most plausible theory I have come across for this is that micro bubbles of air are mixed into the spirit during blending lowering the density and making the proof appear high.  It could of course also be caused by the exothermic blending raising the temperature and decreasing the density, but I presume that you would have corrected for the temperature.  Whatever the cause, leaving the blend to settle for 12 hours or so will give the correct proof.

What is strange in this case is that the second blending immediately gave the correct/expected proof.  Was there any difference in the way you did the first and second blends?  How soon after the first blend was completed did you do the gauging, and how long after the gauging did you add the extra water?

Edited by meerkat
Link to comment
Share on other sites

Give it time for the temperature to settle. Blending is exothermic and temp rises.  As the temp is crashing back to room temp it will make your gauging go all over the place.  Also, allow for all the air to dissipate from the liquid after you stirred it.  The air bubbles will make the hydrometer sink just a tad lower.

Also, if you are in Ohio, make sure you have your State Permit before producing.  Common misconception that the Federal permit will allow you to produce, and may be true in some states.  But in Ohio, you gotta have your State permit in hand before distilling.

Link to comment
Share on other sites

  • 2 weeks later...

Thanks for the advice on letting things settle.   The water I use was at room temp as was the moonshine, so they would be close when mixed.  But, it does seem to change after 4-5 hours.  I am using old school hydrometer (3 point) and a calibrated/certified hydrometer.  

My last run of vodka, I did three tests, ranging from 79.9 proof to 80.00 proof on the nose.    I sent it to a lab in Michigan, and they came up with 79.4 proof.  So, apparently I have to fine tune my process.  


Link to comment
Share on other sites

  • 3 weeks later...
On ‎19‎/‎12‎/‎2017 at 11:30 AM, Killbuck Creek said:

Give it time for the temperature to settle. ........................  The air bubbles will make the hydrometer sink just a tad lower.

Air bubbles can also make the hydrometer float higher if they get attached to the bottom of the hydrometer, spin the hydrometer to shake them off.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Create New...