Friday, March 10, 2017

NIR Color theory... crude

Deciding this was an interesting line of inquiry I acquired a paint sample set from Duracoat.  Many people have taken NIR pictures of their camo clothing, uniform,  rifles, etc but, at least that I have found, none have bothered to dig into more than a couple colors or samples.

My goal is to have a nice camo scheme for airsoft rifles that are NIR compliant and either 1. good generic camo for his airsoft games or 2, awesome sci-fi colors for my tendency to paint things sci fi.   Think of it as stealth-camo.  In the normal visible spectrum it appears flashy sci-fi though non-reflective, but in NIR it is actually a decent NIR compliant camo.  To start I used his plate carrier and hats as a reference and laid the Duracoat samples over them.  I marked out the ones that appear too dark under NIR illumination and gave the names of the rest.  Im seriously considering a more scientific method of comparison... but that always costs money. 

One interesting thing that was unexpected was that some colors like some blues show up pretty light in NIR when in visible they appear much closer to black which usually eats NIR.  Another is Duracoat's "anodized" fascimily paint shows up pretty light.  I suspect they may actually use AlO2 micro or nanoparticles with dye (which is the coating on anodized aluminum) in their paint matrix.   I suspect suspending various polishing powders such as Aluminum, Cerium, Titanium Oxides will yield a visible translucent affect to allow visible observation of the color underneath with minimal visible scatter while the degree of coverage of the particles in the paint will push the NIR scatter rates up to make them appear lighter to the NIR observer.   Tests I did in an earlier post where I had a matrix of rattle cans had vertical lines of paint and horizontal lines of clear coats.  The clears did little to affect the NIR response and so I suspect a clear (such as Duracoat's matte clear finish) suspending an oxide would achieve the desired effect.

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