I was at the pool the other day in some khaki shorts and I got out and sat in a sun chair and spaced out for a while, I looked down and noticed my shorts were darker than they were when they were dry. Now, of course this was one of those 'no shit' moments, but why is it that way? Why do materials get darker when they are wet? I don't mean if a light paint spilled on them, but a liquid that soaked in. Why don't things become lighter when they get wet? Why don't they stay the same?

It suddenly occurred to me when I was thinking. I do not know why things become darker when they get wet. But damn! Now THATS a good question.

Yes...it is the best question I have ever heard on sciforums. And of course, I do not have an answer.

Yeah that is a good question, its one of those things I just accept, like gravity, if gravity never got discovered I'd just think "things fall because they are up".
I don't know, they probably look darker because light reflects slower off moistness or some shit like that. Its always about the light reflecting with these questions.

Doesn't water absorb light?

reflection
refraction
colour distribution
visible colour range
density factor in relation to refraction and prisim effect
(if prism is the rite word{latin thysaurus anyone?})
nature of perception visual
mostly found in most year one university thingeys...
... mostly

:)

I'd like to think that the water speeds up light, creating a timeportal into your anus.

very good question indeed. it must have something to do with the expansion of the material fibres, but that's honestly just a guess. I don't know!

http://www.google.com/search?hl=en&edition=&q=darker+wet&btnmeta%3Dsearch%3Dsearch=Search+the+Web

specifically:
http://www.abc.net.au/science/k2/homework/s95587.htm

I ahve a pair of shorts that get lighter when wet. Figure that one out.

my penis is darker than the rest of my body. very strange, very curious

When a fabric gets wet the water refracts the light hitting it.
This causes the light reflected back to your eys to be less coherent making them appear darker.:D

Originally posted by spookz
my penis is darker than the rest of my body. very strange, very curious

is it wet all the time?

Originally posted by HYPERBAND
When a fabric gets wet the water refracts the light hitting it.
This causes the light reflected back to your eys to be less coherent making them appear darker.:D

I'm not convinced yet

He's sorta right. The water causes the incoming light to reflected and/or refracted, scattering the pink light that would have normally been emitted. Since less light is emitted, less light hits your eye from that certain area, causing it to be darker.

Originally posted by ericfost
He's sorta right. The water causes the incoming light to reflected and/or refracted, scattering the pink light that would have normally been emitted. Since less light is emitted, less light hits your eye from that certain area, causing it to be darker.

Sorta right???
Thats the same answer I posted. :rolleyes:

Originally posted by ILikeSalt
I ahve a pair of shorts that get lighter when wet. Figure that one out.

Its called Erosion!!

:D

Originally posted by spookz
my penis is darker than the rest of my body. very strange, very curious

Wrong hole man!!!:D

Originally posted by HYPERBAND
Wrong hole man!!!:D
It depends... In his Philosophy in Budoir Marquis de Sade explains very convincingly which hole is the right one...oops! Now I gave apendrapew another piece of evidence that I am really a pervert!

About things getting darker when wet, does this apply only to organic compounds (besides none mentioned synthetic stuffs)? I remember reading a book saying that some 'unorganic' materials merely change color when wet......

Originally posted by Grey Seal
I was at the pool the other day in some khaki shorts and I got out and sat in a sun chair and spaced out for a while, I looked down and noticed my shorts were darker than they were when they were dry. Now, of course this was one of those 'no shit' moments, but why is it that way? Why do materials get darker when they are wet? I don't mean if a light paint spilled on them, but a liquid that soaked in. Why don't things become lighter when they get wet? Why don't they stay the same?

You make distinction here between ABSORBENT and non-absorbent materials getting wet.

I remember noticing this thing too---absorbent material, like dirt, getting darker when water soaked into it. Asked a materials science physicist about it some 10 years ago. He wasnt sure.

His theory was to picture the material as partially reflective grains or pebbles.

When dry the light would find its way in and then get reflected and find some zig-zag way out. It would bounce around in the cracks and eventually get out, but at a random angle.

But when water filled all the interstices between the grains or pebbles, then light that didnt come out at just the right angle would suffer "total internal reflection" and be sent back into the material.

so with water soaked material a smaller percentage of the light finds its way back out

this sounds like what some posters on this thread were saying about refraction

as I recall it, the guy was not sure of his answer. could be right tho.

in vague terms I picture the water as helping to lead the light down deeper in among the fibers of the absorbent material and then helping to trap it there by total internal reflection of the scattered light. one could devise an experiment that would vary things about the setup and reveal causes of the darkening

Hi,

The reason things appear darker is as follows:

Rough surfaces scatter incoming light in all directions thus no matter what direction you are looking from, the light seems equally bright. This is called diffuse light.

Smooth surfaces reflect light in a more straight line only at the same angle the light is coming in from, thus when you are looking from a different angle not as much light will reach your eyes. This is called specular.

On a molecular level, water is very smooth thus reflects the light in a more straight line.

When an item becomes wet it is covered in the smoother water so most if the light is reflected by the water and so it appears darker with very bright patches (specular highlights).

Look up specular and diffuse on google to get more info.

I never thought about that before. Wet clothing is not only dark, but it tends to show some glare. I think the specular/diffuse explanation sounds best.

I wonder if there are any effects like wet clothing that are the opposite, such as something that is smooth but then becomes rough without physically alterting (tearing, scuffing, etc...) the material.

Your shorts are made of woven material in a criss-cross directions.
water gets in between the crosses( eg XOX) to form a tiny lens that magnafies the darker inner bits.