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Gunslinger
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The reason why you didn't get any color at all from the face is because a filter and colored light in combination work on a very different principle than mixing two pigments (paint)or two colors of light in a given area.
Colored lenses and filters of the sort can be thought of working in a similar principle as, say, a coffee filter.
A coffee filter will only allow certain things to pass through it. The pigments in the gauge cluster and other non-clear lenses will treat light the same way, to put it in layman's terms (not that I know the scientific terms).
A perfectly clear lens has no filtering capabilities, so nothing is removed from the light passing through it.
A colored lens will only allow light of that color to pass through. To get a little more technical, light and the way we perceive colors is a complicated thing and works on the princple of wavelength, measured in NM or nanometers. The wavelengths of light we see are spread across the visible light spectrum.
Fun fact: this principle is what allows rainbows to happen.
Here's a diagram if anyone wants one.
As you can see, each color has it's own wavelength. To better understand how this filtering principle works, we must understand how we see light and how we can see color. Unit of measure isn't the whole story.
Take something we're all familiar with, a bright red apple. The entire visible light spectrum hits the apple's red skin and every color EXCEPT red is absorbed. The red wavelength bounces off and into our eyes, thus we see red.
Green grass appears green because every wavelength except green is absorbed. Green bounces off into our eyes. Same goes for yellow, blue, purple, etc.
Colored lenses and filters work in a very similar way. Take a coated 3157 amber bulb; again something we're all familiar with.
Tungsten filaments produce warm white light, which contains every color in the visible spectrum. There are different colors of 'white' (warm, cool, daylight) but I won't muddy the waters with that right now.
The amber filament reflects every color except amber back for it to bounce around in the bulb, except the amber wavelength which passes right through. ONLY the amber can pass through. Make note of that, that's important.
In the case of your cluster, you're trying to push pure* yellow light through a blue filter. LEDs that are not white only produce one wavelength of color, in this case yellow. There's all this yellow light bouncing around inside, but it cannot pass through the blue.
At some point you do get what I like to call 'oversaturation' of a filter, at which point the color quality degrades. Much like a balloon, it can only hold back so much before you start getting things other than what you wanted. You can see this effect in color coated bulbs around christmas time. Those blue bulbs are blue, but it's not a rich and vivid blue, usually. However, the amount of light this takes to happen with a colored LED is massive. I'd hate to think how bright that LED would have to be to push past the blue filters.
Welp, there you go.
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