"Hey pal, there's no reason you cant run your likker a second time. It will leave behind more of the water and you will get less volume in the end. But thats the way it works. It will also make your likker more of a neutral but again thats the way it works.
You mentioned your buddies average proof from the first and second runs, remember....we remove water each time we pass it through the still (and flavor too) so it concentrates the product we distill and collect.
What kind of still or should I say tower are they using as compared to yours? that would change things in the end.
As to running tails, you bet you can....and about the heads some will say yes and some will say no. the amount of heads that come from a run are really minimal and are not something I want to drink but you wont die it just tastes shitty to me. I dont re-run any of those compounds but thats just me set aside and re-run if you must. In the long I found that its just not worth the time and effort to keep all that junk around to add the next run.

Good luck and happy hoochin......"

Yes Sir, air it out for a day or so.. I put coffee filters as lids, and then just a jar ring over the filter... Keeps crud out, but lets things breathe..

Heeler's right about the more runs the purer. It all depends on your still to, my pot gets about 60~70% and always did 2 runs for rum and more for neutral. My plated column does 93% single run so don't need to do more. 2 runs for a neutral type drink.

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Use your nose to pick out how much heads are there, but that sounds pretty close. And with those little jars you use thats how you keep THAT compound out of your hearts jars.....great work!!!!"

Ikammer, I use the PSII Column unit that many on here have, and until last week i have never ran mine twice. I usually have an ABV of around 70-80% with a neutral. I made a run with 8 qts finished product last summer and it sat uncut until recently. I cut it with some water i had left uncovered too long and for the first time i got a cloudy product. It tasted ok, but the color was off-putting.

I had another 5 gal batch and i put it in the kettle along with the 8 cloudy qts and ran it as usual. First thing i noted was an increase in ABV, the 2nd qt after pulling off the heads was 94 % !!! That continued until the 4th qt then it slowly fell.

Then i aired it out overnight and cut it the next day to 45%. This finished product was soo smooth it was unreal! My friend asked me if i had watered it down because it didnt burn like it used to. And my old product was loved by all...so that 2nd run definately had its benifits. Will i do it everytime? Probably not, but if im looking for a "special reserve" then i think i will.

Also, when i use my unit as a potstill i get about the same ABV as you have gotten, FWIW
Regards,

Farmin