How do I calculate ABV with a refractometer?

[Fierymac]

Okay - so the title kind of says it all!

If i need to stop the airstill runs at 30% ABV - what reading is that on the refractometer? I've googled it - but it's all relating to equations with original and final SG's - Do i need this info too?

[Mash]

refractometer scale - 80 spirit .jpg

This is what you normally see.....
I fear you may have bougth something else...so what are you seeing ? Brix, Balling or SG?

[myles]

My understanding is that if there is any sugar left in the product then you need to take an SG reading also, and make a correction.
The refractometer result is only correct for a water / sugar mixture. It is intended to measure sugar at a specific temperature in Brix.

For ABV : ABV = [277.8851 – 277.4(SG) + 0.9956(Brix) + 0.00523(Brix2) + 0.000013(Brix3)] x (SG/0.79)

https://byo.com/article/refractometers/

[Easydrinker]

That is a helpful link, that I will come back to tomorrow when more sober.
I bought a refractometer, a while ago, but struggled with it, and stuck with my hydrometer because it was easier to understand!
I do not object to looking like a total dick on this forum if it helps others.!

Robert.

[Mash]

The key thing in that article is that there is more than one type of refractometer.

All refractometers are not the same. Get the right one for the right job and you read the answer from it, because it had been calibrated for the job. Above is for spirit. This is sugar (aka brix scale)

refractometer scale - grapes.jpg

Starting point (original gravity) calculations are normally done in brix with a potential alc on the same scale.
So for sugar additions 1˚ Brix = 1% sugar (ie 10 grams of sugar per litre)

Final alc in beer or wine does require a brix reading and the final sg and some math.

[Mash]

Reread the OP and you are potentially asking 2 questions.

#1 In the title..."How do I calculate ABV "
#2 In text "If i need to stop the airstill runs at 30%"

Answers:

#1 & #2 For spirits ONLY This is as simple as you need to buy a SPIRITrefractometer and read the scale.

something like..
https://www.ebay.co.uk/itm/Alcohol-refr ... SwP9NcUWzr


#1 FOR finished wine and beer ONLY "How do I calculate ABV " is VERY different. As Myles has suggested you need a brix or GRAPES refractometer, a Hydrometer and math.

something like..
https://www.ebay.co.uk/itm/Alcohol-0-25 ... SwcJVdl39k

[Fierymac]

FFS, right, i've made a boo-boo. I thought all refractometers were the same so i've ended up buying one with a brix scale.

It is % spirit that I want to know for doing cuts with an airstill.

Well on the plus side, at least i just need to go back to e-bay and not fart around with calculations!!

[myles]

It is % spirit that I want to know for doing cuts with an airstill.

Perhaps I am misunderstanding here.

If it is a case of when to STOP the run (spirit or stripping) then there are alternatives. Vapour temperature, volume collected etc.
If you are talking about making cuts for product (blending) then I would recommend to do it by taste.

If you want to measure ABV off the still (there should be no sugar involved) then either a spirit hydrometer or a spirit refractometer will work - just correct for temperature.

I do use ABV on a spirit run but only as rudimentary guidance for cuts, and mostly to indicate what size samples I am to collect, and when to change power levels. Final product cuts are done by taste.

[Mash]

The easy answer is buy a spirit refractometer. I have and use both and a hydrometer.

In my 'spirit' pic above. I read that currently as 36.
On an air still, in the next 5 - 10 mins the blue line will slowly drop to 30.
That's where I stop, and turn everything off (or recharge)

Did that answer your op?

[Mash]

FFS. The answer is 12 brix.

I have both. Have just cut some spirit to 30, and read it in brix. 12.

[Mash]

That doesn't mean you are off the hook
Get a spirit one, you will use it... Makes easy work of cutting back too.

[phantom]

hum? lots of "food for thought" here.......

That and some search ideas.........

[Fierymac]

Yes the easy answer is to buy the right damn thing in the first place.
In another post i've been advised to run my air still until it's reading 30% and that the refractometer is more accurate than a hydrometer. So that's what i want to be able to do. My lack of understanding of the right terminology might not have helped. Thanks for the advice folks.

[Mash]

I reckon the only two I use are 30% (for stopping) and 40% (for cutting ).

If 30=12 do you want 40 as well ?

[Fierymac]

I reckon the only two I use are 30% (for stopping) and 40% (for cutting ).

If 30=12 do you want 40 as well ?

that would be very helpful Mash, i could just manage with the brix version then. Thanks

[Easydrinker]

Y'all know that I sometimes argue for the sake of it?
I bought a Refractometer, Brix version, Instructions told me to calibrate it myself with distilled water.
Nothing mentioned/gauranteed how accurately ground the prisms were....
Or how good was my eyesight.
I own Hydrometers from the respected UK company of Stevenson Reeves and various from China land, where people take great pains to ensure the accuracy of the instrument,at the allotted temperature.
For simplicity and ease of drunken use, I will remain a hydrometer man.

Robert.

[Mash]

For simplicity and ease of drunken use, I will remain a hydrometer man.

At least pick an argument that has got enough legs to get started... I mean.. Really..

[Easydrinker]

How very dare you!
More legs than a centipede!

Robert.

[Mash]

Hehe properly lol

[Mash]

I reckon the only two I use are 30% (for stopping) and 40% (for cutting ).

If 30=12 do you want 40 as well ?

that would be very helpful Mash, i could just manage with the brix version then. Thanks

Not scientific or calculated. But derived from two cheap refractometers comparing the same clear liquid multiple times, side by side, on the same day wearing the same shoes

12 brix =30%
15 brix =40%

Both are subject to the word "ish"
Notes about usage:
Temperature OF THE refractometer makes the difference to the readings - such a small amount of liquid, it will quickly be corrected.
Particularly if you take you sample with your finger....and yes the drip is enough.
Strongly coloured liquids also read differently.