Why Do Wet Clothes Appear Brighter or Darker in Color?

[ashwaninair]

Hi All,

I have this doubt from when I was a kid. Could never ask this question to anyone else except myself.

Why does the wet part of a cloth looks bright (or say dark colored). I know its very silly question, but can't think of a reason. Kindly help.

Thanks

 

[brainstorm]

same with paper and with certain kind of hair (more than others - i.e. some blond hair will appear dark wet and others such as bleached blond do not get darker). Good question. Must change how much light is reflected and which wavelengths, but I can't figure out how or why.

 

[pallidin]

More ambient light is reflected with wet clothing. More light hitting your eyes.
This can cause that part of the cloth to appear "brighter" even though the color itself may or may not be enhanced.

 

[licia_ninh]

Actually, refractive index doesn't explain it very much at all.

There is surface reflection at the interface between cloth and air that is due to the change in index of refraction (cloth different from air). The index of refraction of water is closer to that of cloth than air, so it helps the situation. Surface reflection is not colored (not dark in the case of cloth), but the same color as the illumination. Dry cloth has a fairly diffuse surface that scatters that surface reflection in all directions so what you see is a combination of the dark (subsurface reflection) plus the white (surface reflection). When the cloth is wet, it becomes glossy since the water smoothes the surface. That means all the surface reflection goes off at one angle and becomes a glossy highlight. At other angles all you are left to see is the subsurface (dark) reflection and thus the wet cloth looks darker (more chromatic) than dry cloth.