Special coatings in the form of paints that exhibit controlled ratios of sunlight absorptivity to grey-body emissivity control the temperature of structures in space flight. These finishes exhibit good resistance to ultraviolet radiation and do not discolor

Fulk, M. M.

Mayer, R. W.

English

NASA Technical Reports Server

November 1965	 Brief 65-10337 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Special Coatings Control Temperature of Structures 
The problem: To control, by passive means, the 
temperature of structures in space flight, that are 
exposed to sunlight. Certain areas or components of 
such structures may also require selective tempera-
ture control to ensure the adequate functioning 
of the vehicle or its instrumentation. 
The solution: Special coatings in the form of paints 
that exhibit controlled ratios of sunlight absorptivity 
to grey-body emissivity. A given coating having a very 
low ratio will maintain a structure or component at 
a relatively low temperature in brightest sunlight. 
Another coating having a high ratio will maintain 
a relatively high temperature in bright sunlight 
even though the ambient is quite low. 
How it's done: One coating is a brilliant white 
paint having a pigment of 94°/s Ti02 (rutile form) 
and 6% Al 203 and Si0 2 . One part of lecithin is added 
per 150 parts of the dry pigment and the pigment is 
ground to  particle size of approximately 0.1 micron. 
The paint is made by mixing two parts by weight of a 
silicone resin vehicle with one part pigment. This 
thermal coating has an absorptivity-to-emissivity 
ratio of approximately 0.3:1 and is useful in main-
taining surfaces at a low temperature in strong 
incident sunlight. 
Another coating is aluminum in color and its 
pigment is 99% aluminum flakes with 1 0/
 impurities.
A minimum of 98.5% of the flakes is passed through 
a fine mesh (Nb. 325 on the Tyler Standard Screen 
Scale). A slurry is made by mixing the dry pigment 
with xylene. The slurry is mixed with silicone resin 
in proportion based upon 126 g of dry pigment to 
1000 ml of resin. This coating has an absorptivity-to-
emissivity ratio of approximately 1:1 and can be used 
to maintain surfaces at moderately warm temperatures 
in strong incident sunlight although the ambient is 
relatively low. 
Notes: 
1. Both of these finishes exhibit good resistance to 
ultraviolet radiation and do not discolor. Their 
absorptivity-to-emissivity ratios, therefore, remain 
constant over long exposure. 
2. The silicone resin vehicle has a very low vapor 
pressure and so is not subject to serious "out-
gassing" in a vacuum environment. 
Patent status: Title to this invention has been 
waived under the provisions of the National Aero-
nautics and Space Act (42 U.S.C. 2457 (f) ), to Ball 
Brothers Research Corporation, Boulder Industrial 
Park, Boulder, Colorado. 
Source: Marion M. Fulk and Robert W. Mayer
of Ball Brothers Research Corporation
under contract to

Goddard Space Flight Center
(GS FC-444) 
Category 03 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
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Special coatings control temperature of structures

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