Why does a clean car gather condensation faster?

[Nth Degree]

Have you ever noticed that a clean, well polished car has condensation on it sooner than others? I have noticed this over and over again and always wondered what the true reason is? Anyone know the physics behind it? I once thought it was the fresh wax or sealant. But then I once missed a spot while washing my car. That night there was condensation all around that spot, but that spot took much longer to gather the moisture. So I figure it must be either the tiny amount of dirt/dust creating a thin layer of insulation or the the dirt/dust is absorbing the moisture until it is saturated.

[Street Dreams]

The following is backed by no scientific evidence but I am pretty sure I got it nailed.


So basically the earths elements look at a perfectly detailed car and say "how can we mess this up today".


/thread

[C. Charles Hahn]

Have you ever noticed that a clean, well polished car has condensation on it sooner than others? I have noticed this over and over again and always wondered what the true reason is? Anyone know the physics behind it? I once thought it was the fresh wax or sealant. But then I once missed a spot while washing my car. That night there was condensation all around that spot, but that spot took much longer to gather the moisture. So I figure it must be either the tiny amount of dirt/dust creating a thin layer of insulation or the the dirt/dust is absorbing the moisture until it is saturated.

I think you answered your own question....

[SS 07C70]

Have you ever noticed that a clean, well polished car has condensation on it sooner than others? I have noticed this over and over again and always wondered what the true reason is? Anyone know the physics behind it? I once thought it was the fresh wax or sealant. But then I once missed a spot while washing my car. That night there was condensation all around that spot, but that spot took much longer to gather the moisture. So I figure it must be either the tiny amount of dirt/dust creating a thin layer of insulation or the the dirt/dust is absorbing the moisture until it is saturated.

Ever notice that "freezing rain" will freeze on a "dirty" car, before it freezes on a freshly polished / waxed car. At work last year, my boss came back into the office to ask me why, after all day of freezing rain, all the cars in the lot (there all day) were all frozen, but mine was all beaded up with water. ???

[Old Pirate]

I think you answered your own question....

Same here.

[JSFM35X]

Have you ever noticed that a clean, well polished car has condensation on it sooner than others? I have noticed this over and over again and always wondered what the true reason is? Anyone know the physics behind it? I once thought it was the fresh wax or sealant. But then I once missed a spot while washing my car. That night there was condensation all around that spot, but that spot took much longer to gather the moisture. So I figure it must be either the tiny amount of dirt/dust creating a thin layer of insulation or the the dirt/dust is absorbing the moisture until it is saturated.

Beads of water are "deeper" and take more time to evaporate. A car With no LSP will sheet water and the sheet is very thin and evaporates much faster. My idea?

[Nth Degree]

I think you answered your own question....

That`s what I figured. Just wondered if someone had any scientific evidence to explain it.

I really think David is onto something though. Even when nature fails the guy in front of me on the highway will use his windshield washers at 65 mph.

[Todd@RUPES]

The following is backed by no scientific evidence but I am pretty sure I got it nailed.


So basically the earths elements look at a perfectly detailed car and say "how can we mess this up today".


/thread

Exactly!


I think it has to do with surface tension.

Take sand and glue to a piece of non-absorbant plastic (think sandpaper). Mist it will water and the increased surface area of the bumpy surface has zero tension. The water runs to the low spots and appears to `absorb` the water.

Now take a mirror and mist it with water. The water will bead up immediately. This is because (IIRC) water is attracted to itself, so on a perfectly smooth surface it will pull itself into a ball. The (microscopically) smoother the surface the more the bead will stand up.

Dirty cars, or cars with uneven (contaminated) paint are like the piece of sand paper. The water lays downs over the surface (and may evaporate quicker).

[Rayner]

yeah guys... what Todd said... ;-)

Which is probably why its better when an LSP produces finer beading. The smaller droplets will evaporate faster thus collecting less dust.