Some science...
Optical Properties of Circulating Human Blood in the Wavelength Range 400-2500 nm
Absorption spectrum of melanin
Blood approx peak 633nm.
Melanin peak approx 335 nm
Skin colour should have no effect.
P.
PS Apologies for posting this twice, wasn't sure where the thread was going, and nobody else posted facts....
Biting the hand that feeds IT
