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The science behind Louche

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#1 richerich



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Posted 24 July 2012 - 12:00 PM

I'm naive when it comes to science, however something about the louche effect intrigues me. I went on my own to read about the scientific observation and explanation on wikipedia and I'm going to be honest, I still don't get it. It's perhaps the terminologies that are throwing me off. In the simplest manner possible, how would you describe what is going on during the louche?

I'm hoping the simple break down of what is going on will help me to better decipher what is described on wikipedia.


Cheers. :cheers:

#2 Jay


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Posted 24 July 2012 - 12:12 PM

The simplest way I can think of putting it is that the plant/botanical oils derived from grand wormwood, anise, etc. are soluble in alcohol, so you don't see them when they are in a solution of high-proof absinthe. By adding water to a dose absinthe, you are lowering the percentage of alcohol in the glass, and so the plant/botanical oils are coming out of the solution and begin to "reappear" as a result. That cloudy reappearance is the louche.

For a slightly more detailed explanation (and very interesting article), I recommend reading this.

Edited by Jay, 24 July 2012 - 12:12 PM.

#3 Père Ubu

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Posted 24 July 2012 - 12:31 PM

Oil and alcohol mix. Neat absinthe is basicaly alcohol.
Oil and water do not mix. Absinthe ready for consumption is basicaly water.

#4 Artemis


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Posted 24 July 2012 - 12:47 PM

It's all about solubility.
The essential oils that are extracted from plants during absinthe distillation are soluble in alcohol, but not in water. A bottle of absinthe might be 70% alcohol. Think of it as the oil molecules in the bottle being spread out in the solvent (mostly alcohol), so that the liquid looks transparent. When a drink is prepared, water is added, bringing the ratio in the glass to (for example) 30% alcohol and 70% water. Now, in the glass, the solvent is primarily water. The oil molecules are now closer together, not spread out as they were in the bottle; so the liquid in the glass is translucent or opaque.

Edited by Artemis, 24 July 2012 - 12:59 PM.

#5 Gwydion Stone

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Posted 24 July 2012 - 01:18 PM

For a slightly more detailed explanation (and very interesting article), I recommend reading this.

We've had the actual paper posted here since 2008.

To better understand, try this little experiment:

Add a tablespoon of vegetable oil to a jar of ice-cold water. Screw the lid on nice and tight. Shake the living hell out of it. Quickly notice the cloudy liquid. It's cloudy because the tiny oil globs are interrupting light transmission. Watch as the liquid warms and the oil and water separate.

Now imagine that happening on a more microscopic scale.

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#6 richerich



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Posted 24 July 2012 - 05:56 PM

Wow! It's amazing how 0.1% of oil can be responsible for such an effect. I've never had a natural interest in science but the science behind this is too intriguing to be passed on just as a visual miracle. Thank you for the simplification and articles!

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