I’m working on my 40” FTIR system, and I just finished applying a compliant surface. I tested it by attaching the two sides of the LED frame I’ve finished (Environmental Lights’ 850nm LED strip) and pointing my camera at it. The whole surface glows when the LEDs are on, and touching the surface produces no blobs (possibly because the compliant surface is already frustrating the whole sheet, scattering all the IR light).

My compliant surface is thin—three layers of Lexel thinned generously with toluene. The mixing ratio I used is roughly 2:1 or even 3:1. Since Lexel is rubber and other copolymers dissolved in toluene as far as I know, I felt toluene was the best choice of thinners. I rolled it on with a foam brush and ended up with a hard, almost sandpaper-y texture. The grit feels fairly fine—I’d estimate at 300ish grit.

Has anyone had similar problems? Should I attempt to remove the grit by applying a toluene wash? Should I apply more Lexel layers? Should I dissolve the entire surface with toluene and start over? Why does the whole thing glow, anyway? Thanks.

Well, i have no suggestions on the toluene or the Lexel, but if in doubt, try using silicone with tinkerman’s method; silicone is available in almost any hardware store, even walmart.  It comesin a caulk bottle, and it seems to work best for most people.  Just a suggestion if you don’t get any other replies or suggestions.

Good luck!

Seems like you are reflecting the light back because of the Lexel. I would try to wash it all off and then test you set up with just the plexiglass. Don’t think it should be almost like sandpaper the people with the silicone still have a rubber feel.

What sort of projection surface are you planning on using ?

I applied one layer of Toluene diluted GE silicone 1 clear , to the underside
of my Rosco Grey rear projection material. Getting great blobs , really responsive.
Almost Zero Force.

http://www.youtube.com/watch?v=N0WUGbk3zLg

Yes , Your whole surface is being frustrated . 

Wash down the Acrylic , and Either use the GE Silicone 1 in your mix and try again or
Wash down the Acrylic, Apply one thin layer to your RP material or Tracing paper to
place between Acrylic and RP material.

Hope this Helps .