I can't seem to get a clear answer from this one, excuse my ignorance on the subject. When creating a certain liqueur with my former employer, we treated sugars(maple syrup) and other additives(coffee and coffee extract) as water when proofing. I figured the relatively high density of these liquids may skew the results. They were off a bit from treating them like water and we found ourselves correcting with water when we got the results back from the lab with the seamless glass still that gave us a precise ABV. This was an enormous pain in the ass and we found ourselves going back to the lab the better part of ten times before we achieved the desired proof.
TL,DR: What is the best solution to properly proofing liqueurs and spirits with added sugar?
Meerkat who wrote Alcodens is a regular contributor to this forum. He is working on a calculator for that problem.
My suggestion for the moment is to record by mass exactly what you add, then add, then add until you get the correct proof. Next time you make a similar batch you should be very close first time.
an inexpensive glass still and the required thermometer and hydrometer are what's needed. the procedure is in the gauging manual in 27cfr 30.32(c).
in the process, distillation is used to remove the sugars (that are more dense than water and will push your hydrometer up making the amount of alcohol seem lower) with water. then you measure the proof in the usual way.
let me say it again: replace the sugars with the amount of water the sugars displace.
the trouble is that while you are making the batch, you actually can do the weights and arithmetic quite accurately, and your results will be spot-on, but when gauging for tax, you are required to use the prescribed method noted above. you might as well spring for the glass still now.
Hi Will, you have returned, I have missed your gems of wisdom.
Would you mind writing out an example of the math for hitting the right proof when batching a liqueur?