Anti-reflective coating for behind the grill hardware

JohnnyE

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Many vehicles have a fair amount of reflective hardware behind the grill. I am curious what can be done to reduce the amount of IR that is reflected back to a laser gun from these shiny components. Since aesthetics don't matter, what is the best thing to coat/paint/do to this hardware to reduce its reflectivity?

The photo shows a bright aluminum tube right behind my lower grill, and other surfaces that are not radiators. I won't mess with the object further back that has cooling fins. Aluminum is highly reflective. How can I reduce the reflection? It's doesn't have to be pretty or allow visible light to pass while still blocking IR. The finish can be rough or smooth. The only thing that matters is it has to be effective at killing the reflectivity.

This is not about finding an effective anti-reflective IR strategy for license plates or chrome trim (neither of which I have anyway), or headlights and other exterior car and truck parts that have to look nice after the treatment is applied. It's about the ugly "hidden" hardware. Every little bit helps.

Any ideas?

Behind the grill.jpg
 

System

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Are you looking to dull it out for better performance against lidar? If so, I wouldn't worry about it. Get some ALP's and call her a day. There's threads of JTG performance with LED bars :p
 

JohnnyE

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Are you looking to dull it out for better performance against lidar? If so, I wouldn't worry about it. Get some ALP's and call her a day. There's threads of JTG performance with LED bars :p
I am only looking to dull things out to help against lidar, nothing more. It's clearly not about looks!

I have ALP inbound, but under the theory that "every little bit helps," if spending a few minutes shooting rubberized undercoating or something like that on the behind the grill hardware improves my safety margin, I'll do it...if it helps.
 

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Is that chrome part of your intercooler or what is it? Depending on the heat of it, plasti-dip or something similar would help. I wouldn't take a sander to it or anything
 

JohnnyE

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Thanks for the plasti-dip suggestion.

Not chrome, but aluminum. I think it is a liquid-to-liquid heat exchanger/intercooler, and not a radiator to the air. As a result I can't imagine temps exceeding maybe 230°F. I definitely won't do anything to the exterior other than clean with soapy water and acetone, and maybe lightly hand sand for adhesion.

i just have no sense for how well various coating absorb infrared. Visible light, sure, I can see what absorbs versus reflects, but not IR.
 
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grayman

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JohnnyE

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A single stage flat automotive paint is probably the best bet to hold up. Something like SEM bumper paint would do the trick. Or just buy a rattle can at Walmart, LOL

The absolute blackest thing you can actually buy is stuartsemple.com: BLACK 2.0 – The world’s mattest, flattest, black art material
However it isnt really suitable for your application, its "art" paint.
I hear ya.

Since my OP, I've been looking online for ideas, and it's not easy. Picking the right search terms and sorting out the returns is tough. Reflectivity and absorbtion are relative terms.

If a paint or coating is hit by any energy, whether it's white light, IR, UV, microwaves, whatever, a combination of three things will happen. It will reflect a certain amount, a certain amount will pass through, and a certain amount will be absorbed. I remember that much from physics class. Whatever is straight up reflected like visible light hitting a mirror will contain all of the pulses that the transmitter sent out. Not good! That gets us busted. Whatever is passed through will be absorbed or reflected by whatever is underneath.

The amount that is absorbed will be re-radiated, (the energy has to go somewhere), mostly as heat, which is, ta da, infrared radiation. But it will be longer wavelength IR, and it won't have the pulses that the Lidar gun transmitted, which is what gets our speed determined. You can shoot pulsed laser at a block of carbon and it will heat up...may even glow. It will just become warmer than ambient conditions, like a warm engine or radiator. There will be no pulses in the red glow to calculate speed.

What I've seen so far is that carbon black (a/k/a lamp black) is terrific for absorbing IR. Great! Absorb the 905 nm pulses from a Lidar gun, and re-radiate it as long wave IR, warmth, without the pulses. Maybe incorporating carbon black into a clear paint will work? That's what I will try to do. Copper is supposed to be good at absorbing IR as well. Maybe copper-based boat hull bottom paint would work, too.

I wish I had the proper testing equipment!

Edited for spelling.
 
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