From: rlombardo3@gmail.com   
      
   I think the poster meant to say that strongly absorbing materials are also   
   strong emitters, not reflectors.  By definition, strong absorbers can't be   
   strong reflectors.   
      
    - Russ in SB   
      
      
   "Salmon Egg"  wrote in message   
   news:SalmonEgg-203907.09213626122011@news60.forteinc.com...   
   > In article   
   > ,   
   > Shay Ghilai  wrote:   
   >   
   >> Hi there   
   >> we are looking for a flat black (i mean BLACK!!) to be applied to the   
   >> inner aluminum  surfaces of an optical system in the visible range.   
   >> 3M balck has long been discontinued   
   >>   
   >> Any recommendations?   
   >>   
   >> Paint should be durable at -40- +80 deg C   
   >>   
   >>   
   >> TIA   
   >> Shay Ghilai   
   >> sgoptics@netvision.net.il   
   >> sgoptics@gmail.com   
   >   
   > It is very difficult to get a flat black paint. In WWII airplanes with   
   > flat black paint were found to be much more visible in searchlight beams   
   > compared to planes painted with glossy paint. You first need a   
   > specification that including the allowable thickness of the paint.   
   >   
   > The fundamental problem is that strongly absorbing materials are also   
   > strongly reflecting. To get non-reflection, you need a thick weakly   
   > absorbing material of low refractive index. Something like an absorbing   
   > aerogel of low absorptivity that is thick enough would work optically.   
   >   
   > --   
   >   
   > Sam   
   >   
   > Conservatives are against Darwinism but for natural selection.   
   > Liberals are for Darwinism but totally against any selection.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)