ATM List of black coatings from Lick Obs.

[steve@wostx.com (Steve Strickland)]

I found the following in my archives and thought it might be useful.


 Subject: List of Black Coatings
 From: sutin@helios.UCSC.EDU (Brian Sutin)
 Date: 24 Oct 1994 22:06:32 GMT
 Message-ID: <38hb58$1o6@darkstar.UCSC.EDU>

The following is a summary of black stuff from this newsgroup.  Each
method is listed, perhaps with a comment cribbed without reference
from some post.  I have attempted to lean towards terseness.

Additions/suggestions/improvements/flames welcome.

---------------------------------------------------------------------------

Making surfaces non-reflective at grazing incidences seems to be
a problem with two parts.  The first is a black coating which is
non-reflective on a flat surface, and the second is to make the
surface uneven in order to add internal reflections.  Here I have
separated the two methods, even though black coatings often use
uneveness on a small scale to prevent reflections.

Is there some standard for measuring effectiveness?  Albedo at some
standard angles and wavelengths might be appropriate.

Black coatings are:

 1) Krylon Ultra-Flat Black spray paint

 2) A black paint formerly made by 3M, known variously as:

        Nextel flat black paint
        Black Velvet
        ECP-2200 Solar Absorber Coating (3M 34-7016-8832-6)

        This is a spray paint like material that leaves a black velvet like
        nonfrangible surface.

        The technology had been transfered to the Illinois Inst. of Technology
        (312)567-4432 or (312)567-4326 and is sold by the Research Institute
        under the part number MH2200.

 3) Optiklack and Kameralack, made by Tetenal

        "Kameralack" is supposedly more resistant to abrasion, but maybe
        a little more reflective.

 4) Various smoke/anodized coatings:

        (all of these are delicate/frangible)

        Lamp black
            Make "lamp black" using a kerosene or acetylene torch.
            Precipitate fractionated hydrocarbons on a cool metal sheet.

        black nickel

        electroplating with black (oxidized) copper

            This process leaves a dead black coating structured like velvet
            on a microscopic scale.  It has no measurable gloss at any
            incident angle and absorptivity of about .995 throughout the
            visible spectrum.  Any decent electroplating shop should be
            able to produce this for you on most substrate materials and
            it is cheap.

        Black gold coating
            You get a bit of gold in an electrically heated tungsten crucible,
            evacuate then backfill with a few torr of Ar, then heat the
            crucible until the smoke comes off.  It is a delicate coating.

 5) Martin Black

        A proprietary coating my Martin-Marrietta.  Supposedly the best
        from visible to (at least) 15 microns.

 6) AquaDag (a lubricant!)

        A colloidal carbon in an organic binder which bakes away and
        leaves a very rough surface.  If you bake it in a vacuum --
        that is, bake while you're pumping on the system -- the binder
        goes off and it leaves a pretty black coating.

 7) Natural (not synthetic) black velvet

        Surprising good.

 8) Flocked black paper

        Flocked black paper (self adhesive or not) is available from
        Edmund Scientific.  Quick and non-frangible.

Various ways to make the surface rough are:

 1) 400-grit sandpaper

 2) Threads (as inside of tubing)

        Should have sharp edges

 3) Barium Sulfate

        Barium Sulfate has small reflective crystals, which randomize the
        light direction.

Brian Sutin                             sutin@lick.ucsc.edu
Lick Observatory, UCSC                  Santa Cruz, CA 95064
    Fred:   "May I rescue you?"                   `Top Hat,' RKO 1935
    Ginger: "No, thank you.  I prefer being in distress."

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 From: sutin@helios.UCSC.EDU (Brian Sutin)
 Newsgroups: sci.optics
 Subject: List of Black Coatings
 Date: 24 Oct 1994 22:06:32 GMT
 Organization: Lick Observatory UCSC
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