dilution goes wrong - am i stupid

[joschi]

What am i doing wrong, i just don't get it:
had 4 liters with 74 % alcohol,
2 different calculaters say: add 0.55 liter water, should get 65 % alcohol, total volume 4.55 liter.
but i measure now 70 %
(used distilled water, even checked the hydrometer with tap- and distilled water, both show 0 % with pure water, also checked with store bought vodka, shows exactly 40%, everything at room temp. Even rechecked after one day, just to be sure, it's still 70 % instead of calculatet 65 %)

took another bottle (late heads i'm unsure if keeping or not), 1 liter with 76 % alcohol, again 2 calculater say: add 0.25 liter of water should get 60 %, total volume 1.25 liters (took tap water this time), i measure 69 % instead of 60 %

now, calculater would say: 1.25 liters with 69 %, add 0.2 liters of water to get 60 %, i already feel its too little water to get it down to 60 %, isn't it?

Just can't get my head around it, it's annoying ....

[OtisT]

I’m guessing you have a measurement off somewhere.

I use Rad’s calculator for dilution even though it is a bit off. In my experience it’s not as far off as your experiencing. Rad’s calc gives the same answer you got for your numbers. I use it regularly for proofing 60-65% down to 45% (target) and with the recommended volume of water I end up a few % higher than intended, around 47%. When I want to be accurate with final proofing and not guess on the extra water I need to get to my real target, I simply measure ABV and add water twice. Once to get it close (~2% high) then I do it all again to get it exact.

The Rad calc is off because it does not consider the molecular weight of the liquids, only volume. Alcohol is lighter than water for the same volume. I believe that same formula would work exactly as desired if you were mixing by weight, not volume.

[Steve Broady]

Is it possible that your hydrometer isn’t that accurate at high proof? I’ve had that problem before, especially when using a refractometer.

[higgins]

I use an android app called 'Alcohol Calculator for moonshine', which I learned about here on HD. I have found it to be very accurate.

That said, I punched in your numbers (4L at 74%, dilute to 65%) and it said to add .58 L water, very close to your .55.

I'd have to guess that your initial ABV reading is off. To add .55L water to 4L alcohol and get 70% you'd have to start with 79% ABV.

[joschi]

Im just off to much, i just did another test:
start 0.6 liter with 70 %, calculater says to add 0.1 liter water, should be 60% (note: in the one liter vessel, the sample is "missing"!), i get 63 %, well not so much off, but still 1/3.
i even pour a little in the vial, because there is always a drop or two at the bottom, pour back, then fill the vial for measuring.
as mentioned: the hydrometer is testet with store bought vodka, was very accurate at 40%.

i think i will buy another hydrometer, maybe one from 20 - 80 % or so, should be more accurate then 0 - 100 % ?
btw: i measure usually something around 80% when start collecting (pot still), very plausible, not? (this time, my hearts where a bit higher, usually about 70%, because my low wines were over 40%, i had some faints (heads+tails) left from previous runs, just for info)

[EricTheRed]

I use this one.
https://play.google.com/store/apps/deta ... distillers
From a member here.

[greggn]

2 different calculaters say: add 0.55 liter water, should get 65 % alcohol, total volume 4.55 liter.
but i measure now 70 %

How soon after proofing are you taking measurements ? When blended the alcohol/water mixture will give off a lot of heat ... certainly far and above where your hydrometer is calibrated.

I always let it sit a day and then measure the next.

[joschi]

one day later it's the same proof. I have a store brought unopened absinthe with 70%, would that be fine to "calibrate" my hydrometer? I know that "stuff" in the likker (like sugar or whatever) can throw off the measering.
it just doesn't let me sleep, well well, i will buy another hydrometer, it's always good to have a spare one anyway, i don't trust mine anymore now...

[jonnys_spirit]

It's good to have a second and third in different ranges but expect to be more confused when they all show different readings lol...

Proof it close and dial it in by how it feels in your heart and soul. Offer some to the likker gods and throw one back... Don't lose sleep over it. It doesn't need to be exact - it just needs to be where it's good for you

Cheers,
jonny

[NZChris]

Are you temperature correcting your readings?

Personally, I use a calculator to work out the finished volume, then make it up to that volume. That way, I don't have to worry about contraction.
If I'm making up a larger volume than my measuring equipment, I use TTB Table 6 to work out the weights of each to use.
viewtopic.php?t=79748

[Stonecutter]

one day later it's the same proof. I have a store brought unopened absinthe with 70%, would that be fine to "calibrate" my hydrometer? I know that "stuff" in the likker (like sugar or whatever) can throw off the measering.
it just doesn't let me sleep, well well, i will buy another hydrometer, it's always good to have a spare one anyway, i don't trust mine anymore now...

I would suggest using some store bought vodka to verify accuracy.
Make sure it’s the same temperature as what you’re proofing.

[Steve Broady]

I would suggest using some store bought vodka to verify accuracy.
Make sure it’s the same temperature as what you’re proofing.

+1

I’d suggest a bottle of Everclear as well. Quality aside, you should be able to rely on the ABV on the label. Make up a few different proofs if you like, but that will help you check your equipment at higher proofs.

[Setsumi]

Volume * % alc = volume of 100% alc. Volume of 100% alc / diluted alc = volume of diluted.

4l * 0.74 = 2.96/0.65 = 4.55l - 4l =0.55l.
I find the alc meters with 0 to 100% scale to off at both high end and middle end. BUT unless you need laboratory accuracy it is just academic and you can adjust the volume to reach your desired %. If you have an opprtunity verify your meter against lab grade alc at both 90%, 60% and 40%. But then you will always know that your azo is not that.