Evaporated whisky inspires new type of coating technique

March 25, 2016 by Bob Yirka, Phys.org report
Evaporated whisky inspires new type of coating technique
Credit: arXiv:1602.07937 [physics.flu-dyn]

(Phys.org)—A team of researchers at Princeton University, along with assistance from a photographer in Arizona, has uncovered the secret behind why whisky does not leave behind "coffee rings" when in dries. In their paper published in Physical Review Letters, the team describes their analysis of various whiskies and other fluids and why they believe their results suggest the possibility for a new type of industrial coating.

When coffee is spilled and allowed to evaporate on a surface, it typically leaves behind a ring, which has come to be known logically enough, as the coffee ring effect. It happens because the coffee evaporates more quickly at the edges, which leads to a change in , which causes more coffee (and the bean residue) to be pulled to the edges where it dries. Not all liquids behave this way though.

Ernie Button, a photographer living in Arizona noticed one day that the residue left behind when whisky (or 'whiskey' for some brands) dried in a clear drinking glass, was starkly dramatic when lit from below with various colors—he began photographing such residue and eventually noticed that not all whiskies left behind interesting patterns—that led him to ask a physics friend what was happening with the whiskies. That friend set up a team at Princeton to investigate the drying properties of whisky.

Upon taking a close look, the research team found that those whiskies that did not leave behind a coffee ring type pattern when they evaporated, had two important features: the first was fat-like molecules that lowered surface tension–as the liquid evaporated they collected on the edges of the drying surface which in turn caused the creation of a tension gradient that pulled the liquid back inward. The second feature was plant-derived polymers that caused a sticking effect, which in turn helped to channel particles in the liquid to the base material (the ) where they stayed stuck.

The researchers confirmed their findings by creating liquids that behaved in the same way as whisky, and then by removing either the polymers or surfactants—doing so prevented the liquid from leaving behind non- ring characteristics. The researchers also noted that because of its even coating distribution characteristics, whisky-type liquids could very well prove suitable for industrial coatings or even as a type of ink for 3D printers.

Explore further: Exploring amazing patterns left behind by drops of whisky left drying in the tumbler

More information: Hyoungsoo Kim et al. Controlled Uniform Coating from the Interplay of Marangoni Flows and Surface-Adsorbed Macromolecules, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.116.124501 , On Arxiv: http://arxiv.org/abs/1602.07937

ABSTRACT
Surface coatings and patterning technologies are essential for various physicochemical applications. In this Letter, we describe key parameters to achieve uniform particle coatings from binary solutions. First, multiple sequential Marangoni flows, set by solute and surfactant simultaneously, prevent nonuniform particle distributions and continuously mix suspended materials during droplet evaporation. Second, we show the importance of particle-surface interactions that can be established by surface-adsorbed macromolecules. To achieve a uniform deposit in a binary mixture, a small concentration of surfactant and surface-adsorbed polymer (0.05 wt% each) is sufficient, which offers a new physicochemical avenue for control of coatings.

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6 comments

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antialias_physorg
5 / 5 (4) Mar 25, 2016
Just goes to show you can find interesting and useful effects wherever you look.

But I wonder how they got their research material approved.
"Liquor store bill" is certainly a hard one to get past a review board.
Mark Thomas
5 / 5 (3) Mar 25, 2016
Hilarious that it took centuries for anyone to allow enough whiskey to evaporate in a glass to notice the effect and investigate. Whiskey may have all sorts of properties we are unaware of, and never will be. :-)
nilbud
1 / 5 (1) Mar 25, 2016
Whiskey is spelled whiskey the scotch make a copy called whisky which is basically alcohol with burned turf dumped in it.
malapropism
5 / 5 (2) Mar 25, 2016
@Mark
And why did the photographer leave enough whisky behind in the glass that the effect got noticed? Certainly I've never left that much, nor for so long... But perhaps it was an inferior drop? :-)
Captain Stumpy
5 / 5 (1) Mar 26, 2016
And why did the photographer leave enough whisky behind in the glass that the effect got noticed?
probably recovering from a hangover

.

Whiskey is spelled whiskey
@nilbud
1- whisky[ey] is just a term for a specific type of spirit distilled from fermented grains

2- the differences in spelling are generally due to exposure and marketing : American and Irish tend to favor the spelling WHISKEY, while CAN, Scot's, and Nippon tend to favor WHISKY
Whiskey/whisky nmemonics:
...Countries that have E's in their names (UnitEd StatEs and IrEland) tend to spell it whiskEy (plural whiskeys)

Countries without E's in their names (Canada, Scotland, and Japan) spell it whisky (plural whiskies)
http://www.thekit...i-100476

Captain Stumpy
5 / 5 (1) Mar 26, 2016
But I wonder how they got their research material approved
@AA_P
they took it out of their taxes as business lunches?
LOL

if i were writing to the gov't to get $$ for a grant, i would hide it in plain sight by making up names that are close to correct (or just descriptive) LMFAO:
1- psychoactive ethanol liquid concentrate solutions
2- dose variant Quasi-euphoric depressants
3- concentrated distilled ethanol solution products

i got my commander to authorize funds for a test of "Tracking specific location dependent gravitational anomalies due to concentrated solutions of psychoactive liquid depressants" so we could have a welcome back from Afghanistan party!

it is all in the way you word it

i am willing to bet that yall can come up with some far more ingenious ways to hide a bottle of Chivas in plain sight
LMFAO

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