Why are wet materials transparent?

[dotancohen]

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?

 

[gsal]

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...

 

[dotancohen]

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.

 

[256bits]

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.

 

[Drakkith]

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.