What to look for in the glass

[Creggor]

Hello, Is there any truth to this?? I have heard that after your pour a drink

into a clear glass you are to swirl the drink around a look at how it comes

down the sides of the glass. Something about the oils in the grains or something

of higher proof products seem to drip back down into the glass in many smaller

little trickles and the lesser aged products seem to come down in bigger sheets.

Is there any truth in this or have I had to much to drink tonight. Creggor

[Guest **DONOTDELETE**]

The thin trickles are called "legs" and I think it's the alcohol content, not the barrel age, that makes the difference. I imagine we're both about to be educated on this...

=John=

http://w3.one.net/~jeffelle/whiskey

[tdelling]

I threw "legs of wine" into google, and got this:

http://www.wineeducation.org/frames/legs.html

which does a fairly poor job of describing the phenomenon, although

it does tell ya about widespread beliefs in the wine community.

Short explaination: much like "holding a bead" (old moonshiner's method

for measuring alcohol content - ask about it if you've never heard of it),

looking at the legs can give you an idea of alcohol content.

No legs = little alcohol. Number of legs somwhow correlates with

alcohol content, but I'm not quite sure if more legs means more

alcohol or less alcohol. If anyone cares, I can go mix up a few

ethanol/water solutions and figure it out.

Long explaination: a liquid will cling to the wall of a glass and rise

up the side to a height that balances the surface energies (or surface

tensions) of the liquid/air interface and the liquid/glass interface.

The liquid is happy to spread up the glass because it likes touching

glass, but on the other hand, when it spreads up, it also "touches"

more air, and it doesn't like touching the air very much.

An easy way to measure this is by just putting a drop of the liquid

on a flat piece of glass and looking at the shape. Very round drops =

not likely rise up the glass ; flatter drops = will rise up a glass.

A word about the air/liquid surface tension: Water has a high surface

tension (you can set a paperclip on water and it will set on the

surface), while ethanol (and ethanol/water solutions) have lower

surface tension. Thus ethanol (and ethanol/water solutions) will

rise higher up the side of a glass than pure water.

So what happens is that the low surface tension liquid (ethanol+water)

climbs the side of the glass. Ethanol evaporates faster than water, so

pretty soon, the amount of ethanol in solution is much less, and the

surface tension of the liquid goes up. Now all of the sudden, the liquid

doesn't want to climb so high on the glass, so it will spontaneously "de-wet"

in order to decrease the amount of liquid/glass interface. It bunches up

into "legs" just like water will bunch up into droplets on wax paper.

Since the phenomenon depends on having ethanol in solution (and the

ethanol evaporating), you can see how it'll only happen if there's

sufficient ethanol in solution. And de-wetting behavior is certainly

also dependent on ethanol concentration, and so (among other things)

ethanol concentration will determine the number of legs, and how they

behave.

Sometimes you can sit and watch the liquid climb up the wall, then de-wet

and crash down when the ethanol evaporates, then rise up again, and then

fall down again... three or four times per second.

Hope this was somewhat clear. Feel free to ask more and I'll tell ya more.

Tim