Why are wet materials transparent?

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Discussion Overview

The discussion centers around the phenomenon of certain materials, specifically paper and cloth, becoming transparent when wet. Participants explore the reasons behind this change in transparency, considering the interaction of light with water and the structure of the materials involved.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that the transparency of wet materials like paper and cloth is due to water filling in the gaps and cracks, reducing light scattering.
  • Others argue that the phenomenon is specific to thin, porous materials that allow light to be refracted through the water present within them.
  • A participant mentions that the effect may not apply to all wet materials, suggesting that the discussion should focus on particular types of materials.
  • One contribution discusses the role of reflections when water saturates paper against a surface, indicating that the arrangement of layers affects light transmission.

Areas of Agreement / Disagreement

Participants generally agree that not all wet materials become transparent, but there is no consensus on the exact mechanisms or conditions that lead to transparency in specific materials like paper and cloth.

Contextual Notes

The discussion does not resolve the underlying assumptions about the nature of light interaction with different materials, nor does it clarify the specific conditions under which transparency occurs.

Who May Find This Useful

This discussion may be of interest to those studying optics, material science, or anyone curious about the properties of light and materials in various states.

dotancohen
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Many materials, such as paper and cloth, are transparent when wet. Of course I understand that water is transparent, but why does a non-transparent material become transparent when something is _added_ to it? If there is some material that blocks the path of the photons, how does adding yet another layer make it suddenly not block them?
 
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Disclaimer: I don't know what I am talking about.

Having said that...

This does not happen to ANY wet materials...you immediately narrowed this down to thin, very porous materials like paper and cloth...

I would venture to say that in these cases, the material gets wet through and through and so there is water throughout the material, exposed to light on both sides...and because light can enter water and be refracted, you end up seeing it on the other side...
 
gsal said:
This does not happen to ANY wet materials...you immediately narrowed this down to thin, very porous materials like paper and cloth...

Perhaps you mean that this does not happen to ALL wet materials. You are right, I should have mentioned that the phenomenon affects only particular materials. However, it is worth noting that those are the materials that super-secret messages are mailed in and women's breasts are covered by, so they are arguably important materials to be able to quickly transform into a transparent state.
 
Adding water to the paper that is up against a surface results in only one reflection at the body and back out to your eye through the water saturated paper. Adjust the water saturated paper so it is not touching the body, and you have another reflecting surface ie the paper and air.
 
dotancohen said:
Many materials, such as paper and cloth, are transparent when wet. Of course I understand that water is transparent, but why does a non-transparent material become transparent when something is _added_ to it? If there is some material that blocks the path of the photons, how does adding yet another layer make it suddenly not block them?

To my knowledge the paper is already transparent slightly. I could see adding water reducing the random scattering of light from the surface since the water fills in all the cracks and such.
 

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