3M used to make a paint for optics which has a reflectivity near 0%.

It has a very volatile solvent that flashes off when baked.  We used  
it in spectrofluorometers we used to make.  Never contaminated mirrors  
or the grating.  I wouid be interested to hear if they still make it.

Bob Landman
H&L Instruments, LLC

Sent from my iPhone

On Mar 29, 2010, at 8:24 AM, "Glidden, Kevin" <[log in to unmask] 
 > wrote:

> Good Morning, and Happy Monday.
>
> A couple of questions for anyone:
>
> We have a lighting application where we are getting light reflection  
> off two specific solder joints (we're so lucky to still use Sn63Pb37  
> they are just TOO shiny!), so I am looking for a method to cover  
> those joints with a black (or dark gray) sealant.  This would need  
> to be a low out-gassing material.  Does anyone know of any such  
> material?  Is there such a thing as black pigmented conformal coating?
>
> The second question would be for this same product.  I also have a  
> need to seal around the base of some LEDs to prevent moisture  
> ingress to the bottom only terminations.  Would perimeter sealing be  
> sufficient?  How does one determine when they need to underfill vs  
> perimeter seal?
>
> Thanks!
>
> Kevin Glidden
>
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