Why Do Wet Clothes Appear Brighter or Darker in Color?

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Discussion Overview

The discussion revolves around the visual perception of wet clothing and other materials, specifically why they appear brighter or darker when wet. Participants explore the underlying physical principles, including light reflection and refraction, as well as the effects on different materials like cloth, paper, and hair.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses a long-standing curiosity about why wet cloth appears different in color, seeking explanations.
  • Another participant notes that similar effects are observed with paper and certain types of hair, suggesting a relationship between wetness and light reflection.
  • A participant proposes that more ambient light is reflected from wet clothing, which could make it appear brighter, though the actual color may not change significantly.
  • One participant challenges the sufficiency of refractive index to explain the phenomenon, discussing how surface reflection changes when cloth is wet, leading to a glossy appearance that alters perceived color.
  • The same participant elaborates on how the interaction of light with wet surfaces results in a combination of surface and subsurface reflections, affecting the overall appearance of the material.

Areas of Agreement / Disagreement

Participants express various viewpoints on the mechanisms behind the color change of wet materials, with no consensus reached on a singular explanation. Multiple competing ideas about light reflection and refraction are presented.

Contextual Notes

Some assumptions about the nature of light reflection and the properties of different materials are not fully explored, and the discussion does not resolve the complexities of how these factors interact.

ashwaninair
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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
 
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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.
 
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.
 
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.
 

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