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schrizto
10-04-2006, 04:16 PM
Can someone explain how when coffee is spilled a ring is formed around the edge of the spill, while spills of other liquids do not? Is it something only in the coffee that does this?

spingears
10-04-2006, 05:03 PM
Can someone explain how when coffee is spilled a ring is formed around the edge of the spill, while spills of other liquids do not? Is it something only in the coffee that does this?WAG Surface tension?

gotpasswords
10-04-2006, 05:39 PM
The key is probably the botom of the mug - it touches the table as a ring, rather than a disk, as in a typical tumbler or "iced tea" glass.

susan
10-04-2006, 08:32 PM
I don't have the experience you do. I perceive that most, if not all, fluids leave rings. Maybe the difference is the kind of cup you use. I drink just about everything out of a mug.

MikeS
10-04-2006, 10:01 PM
A professor in my department actually investigated this question some time back. Here's an article on it (http://chronicle.uchicago.edu/971023/coffee.shtml).

Beware of Doug
10-04-2006, 10:33 PM
You can spill your coffee and get one of these (http://www.landolakes.com/mealIdeas/ViewRecipeLarge.cfm?RecipeID=6326B)? I'm drinking the wrong brand of coffee.

schrizto
10-06-2006, 02:37 PM
Actually, what I alluded to in "coffee rings" wasn't the ring that is formed by a mug, but the dark ring that appears when a coffee spill dries up.

Hampshire
10-06-2006, 02:49 PM
I think the cup or mug is what creates the ring. Coffee spills down the side of the container then moves along the edge of the ring.

I don't think you can just pour some coffee on a flat surface and have a ring magically form.

Squink
10-06-2006, 03:03 PM
Actually, what I alluded to in "coffee rings" wasn't the ring that is formed by a mug, but the dark ring that appears when a coffee spill dries up.MikeS got it then:Here's an article on it. (http://chronicle.uchicago.edu/971023/coffee.shtml)

Basically, there's more evaporation at the edges of the drop than in the middle, so solutes are drawn to that outer ring. I've seen the same effect with colored Kool-Aid.

Hampshire
10-06-2006, 03:05 PM
I think the cup or mug is what creates the ring. Coffee spills down the side of the container then moves along the edge of the ring.

I don't think you can just pour some coffee on a flat surface and have a ring magically form.

Sorry, I thought you were talking coffee rings like these (http://www.camarada.org/images/postcard_ab3.jpg)

susan
10-06-2006, 10:28 PM
As did I.

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