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[ATM] Black Powder
The blackest thing I know is the aperture of a large cavity that is nearly
black inside. In telescope making, we try to approach this level of
blackness with powder (millions of tiny cavities) and with baffles (a few
large cavities). Perhaps if BOTH are used, superior blackness may be
had.
Most black coatings (I have no experience with powder) provide specular
reflection at grazing angles, so it is important to keep the surface area
subject to grazing incident light minimized. I guess this means that
baffles should have sharp edges.
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Date: Sun, 18 Nov 2007 16:59:42 -0800
From: "Bob May" <rmay@nethere.com>
One of these days I'm gonna grab all of the different kinds of
black out there and see what really is BLACK. I just tried some
Rustoleum textured black and that is rather black. I'bve got
several other blacks including some Floquil engine black - all of
the Floquil colors are very flat and the engine black is the dead
black.; The thing is to measure the rreflection at a very slight
angle of say two degrees and see how much of a light source is
reflected to the photosensor.t.net
Bob May
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