Stain: Newsletter Challenge (06/20/06)

as the outer edge dries, capilary action draws more liquid outward, depositing the solids in a ring.

I don't know what happens really...Jeeves cleans up after us.

What is a "ring-link?"

That should read "ring-like". I've corrected it.

It could be ring link because it links the unevaporated deposits together. Ok, I might be wrong. This is my take on it. Right or wrong I'll spout it out. The material is suspended in the fluid,and is quite happy to stay there. Essentially, the material is trapped in the fluid and will flow in the direction the fluid is traveling. In this case liquid on a flat surface is will continue to travel to its edges as it eveporates because nothing is holding it like in a cup. what I don't know is why this occurs. Gravity?

When a drop of wine or soda on the kitchen countertop, the drop is not in a flat surface. Observe carefuly and you can see a convex shape.

The other ring of the drop will be the tinner towards the surface of your kitchen countertop and it dry easy as copmpare to the inner or center of the drop. The fluid will flow in the direction the fluid is traveling. In this case liquid on a flat surface is will continue to travel to its edges as it eveporates as we know that the gravity will pull all partical down.

As the outer ring dry up, fuild will continue to flow towards the ring. That why you get a stain ring on your kitchen countertop

It's a fairy ring and thay leave the ring to show thanks for the donation to the Gods

Oh yeah, I'm with this guy!

I really don't have that problem, 'cause I don't drink wine or soda, but if I did, I'd bet any spilled drops would spread out because of the detergent and grease mixture that coats my counter tops.

I wouldnt know. I'm Canadian and drink beer.

I give you an "Aye" for that answer.

My dog licks up eveything, so the house is spotless. However, I have spots that seem to magically appear all over my lawn!!!

That is a crop circle in your yard, or did I mis spell crop? Miss

That's too funny!

Of course! Wut else does a dogdo?

Yeah, dog eat, sleep and do the thing they usually do.

The ring appears because evaporation at the edge is faster than even a short distance in from the edge, where the surface is flat. This causes flow towards the edge. The higher evaporation at the edge is described by Thomson's law, which says basically that equilibrium vapour pressure increases as the radius of curvature of the liquid surface decreases (as viewed horizontally in this case). It's also a function of surface tension.

Good, but only part of the answer. As the evaporation proceeds from the edge, salt
(or sugar),is deposited.
The higher concentration of solute draws more solution to the outer 'ring` thus the depost is
thicker at the edge of the drop.