[MF3D.FORUM:925] Re: Black mount obsession?

[Tom Hubin <thubin@xxxxxxxxx>]

> Not to be combative, but a lot of people use them with the
> white side forward and the back in black (often for projection
> reasons, presumably).

I'd like to know why. I have seen it done but it makes no sense to me.
Absorption of IR and light by the black surface will contribute to
heating the mount and the slide. White on the projection side makes the
mount more visible on the screen.
 
> BTW, did you ever look at a single black RBT mount half in a
> red button?  Lost of light comes through.  Not as much as the
> white half, of course, but it's amazing how much light comes
> through the black plastic.

The transmission charactereistics of the material are not related to the
reflection characteristics. White reflects well over 90% of the incident
light. Black reflects well under 10% of the light. Maybe as little as
1%. The remaining light passes through the material and may or may not
be absorbed. 

A metel mount will not transmit light, no matter what color it is on the
surface. A clear plastic mount could be painted almost any color and
pass too much light. Choose the material for low transmission per mm of
thickness. Test it if you cannot get numbers from the manufacturer.

Tom Hubin
thubin@xxxxxxxxx
AO Systems Design