Comment on Eight sunscreens that failed their SPF claims tested by same overseas lab

• modeler@lemmy.world ⁨2⁩ ⁨months⁩ ago

  Where else could the energy go?

  It could be absorbed by the material and converted to either

  • a lower wavelength (i.e. uv fluorescence) or
  • heat (eg black cars are hotter than white cars in the sun)

  In both cases the wearer is protected from uv, but the the spf will be found to be artificially low.

  source

  • Balthazar@lemmy.world ⁨2⁩ ⁨months⁩ ago

    Both of those would be detected as light coming back, but with different spectra and geometry, so fair enough.

    source