Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Tranluscence of wet paper

  1. Feb 11, 2012 #1
    Why does a wet piece of paper let through more light than a dry one?
  2. jcsd
  3. Feb 11, 2012 #2
    Most of the change in transparency of paper [and tee shirts] to allow more light thru when wet is probably because the water reduces the surface irregularities by holding them together, flatter, reducing reflection.....it makes the surface 'smoother'.

    More here:
  4. Feb 11, 2012 #3
    Yes. In fact, if you wet it with an organic solvent whose index matches that of the paper, it will become transparent and allow you to read the letter inside an envelope without opening it.
  5. Feb 11, 2012 #4

    Andy Resnick

    User Avatar
    Science Advisor
    Education Advisor

    Because there is reduced scattering, due to the change in relative refractive indices of paper/air vs. paper water. Lower Δn, less scattering.
  6. Feb 11, 2012 #5
    Thanks.That helped.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook