Obscuration Value

[BWK]

Hey Guys,

I am currently applying for a distillers licence and have come across the term 'obscuration' in the ATO's guidelines to distill.

The ATO says this:

"Obscuration is the alcohol obscured or undisclosed by matter such as sugar or colouring in an alcoholic beverage. Add the obscuration to the apparent strength to give the actual strength of the sample. The obscuration figure is normally obtained from the distiller's laboratory test results. Obscuration can be determined independently using a Thorpe's Still."

Could someone explain how to get this Obscuration Value? I assume using a glass still to redistill a portion of your spirit to determine alcoholic strength would negate the need for this value? Or am I being naive?

Thanks in advance!

[Stonemaker1]

I had enough trouble with the ATO still permission, good luck with the obscuration... :laughing-rolling:

[ThePaterPiper]

If you aren’t adding any colouring or sugar, this shouldn’t be a problem for your produce. Some spirits have added colors, which depending on their own specific gravity, will change the solutions gravity, as would sugar, making the alcoholometer float higher in the fluid reading lower abv. Sugars, when in solution, as opposed to water, actually occupy the space between alcohol molecules, so the gravity changes, but the volume doesn’t. The same may be the case with some colours like caramel, which is often used in whisky.

Oh and can you keep us updated as to how you go with this? I found just looking at the paperwork required here in NSW intimidating enough, let alone the extortionate amount of excise the ato want for your efforts.

[Professor Green]

In a straight ethanol/water mix, a hydrometer is going to be reasonably accurate however for anything that has flavour such as rum/whisky/whiskey/gin/absinthe, the components that provide the flavour will throw the hydrometer reading out by changing the specific gravity of the liquid being measured.

I think you either need to get a sample analysed at a lab to determine the obscuration factor then apply that to the hydrometer reading OR use a Thorpe's revenue still in the manner outlined by the ATO to figure out the alcohol content.

Also, please pop into the welcome centre and introduce yourself. :handgestures-thumbupleft:

Cheers,
Prof. Green.

[Dyno]

I think you may need an Ebulliometer. In fact I’ve been told that you do need one or you will be directed to out source at an approximate value of $380 plus per sample. They cost anywhere from $1500 upwards. I may of been given a bum steer, I hope so but in same boat as you by sounds of things.
Have also been in discussions with Council re D.A and that’s a head screw all on its own. How far have you got with the local Council? I’d assume you’ve done that process first before baring your soul to the ATO ?

[BWK]

Thepaterpiper- I can most definitely. It’s actually a bit of fun running around trying to figure things out.

Professor Green- Yeah ok, so redistill product with a Thorpe’s still. I had such a difficult time finding out what a Thorpe’s still was, every Google entry resulted in a news article about Ian Thorpe!

To Dyno - Yes local council are all too happy to oblige, they think it will be good for the area!

This community is God sent I tell you what!

Cheers

BWK

[ThePaterPiper]

Not sure if you found this, but there appears to be three methods of calculating the obscuration value (at least acceptable in the US. )

Here’s a link to the page. https://www.law.cornell.edu/cfr/text/27/30.32

Doesn’t seem too arduous.