Interesting information about Heat

LED Flashlights – General Info
1

In short words, today I discovered that, if a material's color is BLACK, it will dissipate heat better.

http://en.wikipedia.org/wiki/Black_body (See Planck's law)

The reason black paint dissipates heat more than any other color is that black is the most capably dissipative color for infra-red (heat) wavelengths. As we all know, back is very absorbent when energy rays (visible AND invisible) such as sunlight hit it. It is also able to cast off the most heat energy, all of its radiation being in the infra-red part of the energy wavelength spectrum. Single colors tend to focus their ability to both absorb AND dissipate in the wavelength of their color, and far less in the infra-red compared to black.

So, I'll start buying only black flashlights

2

Can tell stories about this. Used to be a physics teacher a lifetime ago.

Black radiates better - but take into account the barrier resistance of the coating.

Won't work where the air temperature is close to the body temperature though.

Delta T is important.

3

There are some surprises though.

A body that's black in the visual range might actually be much more reflective (i.e. less absorptive and emissive) in the infrared. I've seen dark colors becoming pretty much 'white' when 'seen' in IR (NIR in that example).

And if I'm not mistaken, white radiator varnish paint is much less "white" in the (F)IR.

4

This is one of those areas in Physics where they really started to lose me.

5

has to be pretty negligible difference

6

An electronic engineer told me that it could affect up to 20%, it is a big difference but that is not for every case (he told me a comparison between heatsinks from A-B Class audio amplifiers).

For that reason lots of heatsinks are black, but I don't really know how could this affect flashlights...