On 10/08/2012 08:50, newshound wrote:
On 09/08/2012 22:54, Martin Brown wrote:

Basically any shiny metal behaves to some extent as a reflector of IR
wavelengths. Most resin paints and common materials are black in the
thermal IR including glass windows.

Regards,
Martin Brown

I'd love to find a reference for your comments on paints. I have a work

It is a slight over simplification but basically true for most paints.

Work in this area is not much in the open literature but some is for the
paints used on major observatory domes. Brief intro here a few searches
on ADS abstracts should get you more detail:

http://www.umich.edu/~lowbrows/refle...1/tryan.5.html

Basically the old way was to use extremely white paint to keep solar
heat out of big observatory domes. Now they use a cunning mix of white
and aluminium to get thermaly neutral paint at night. Otherwise the dome
surface supercools to the night sky and cold air drips in through the
open dome slit producing local severe turbulence in the seeing.

Other variants include base coat clear technology where the undercoat is
shiny metallic to reflect most light and the top coat varnish is as
close to being black in the thermal IR band as they can make it.

Another intro:

http://www.pcimag.com/articles/intro...ctive-pigments

There are military applications to adjusting your thermal IR emission
signature.

job at the moment where this is a very real issue. IR spectra by ATR
show relatively narrow absorption bands with high transmission in
between. These are paints on blast cleaned (i.e. rough) steel. Are we
getting absorption at the metal-paint interface? Coating thickness is
200 - 250 microns, two pack epoxy and polysiloxane "white" paint.

Is the white TiO2 pigment? I am a physicist and not a proper chemist but
I can ask my wife who is tonight. I have no experience with ATR.

Asking your paint supplier tech support is probably your best bet.

Regards,
Martin Brown