[Svartalfiar]

The fact that true white reflects all colors and true black reflects none is immutable fact, and is not dependent upon whether you’re mixing paint, printing something from your home printer or baking a cake.

So what happens when you mix two substances, one of which reflects green light, and a second that reflects red light? You don't get orange, you get brown. When you're mixing paint or ink for printing, you aren't adding the light they reflect together, you're adding the light they absorb together. Each color you add, is taking away the colors that it isn't.

https://graphics.stanford.edu/courses/cs178/applets/colormixing.html

http://www.colorbasics.com/AdditiveSubtractiveColors/

[LIConFem]

"So what happens when you mix two substances, one of which reflects green light, and a second that reflects red light? You don't get orange, you get brown. "

What the heck does that have to do with anything???

We're not talking Watercolors 101 here. And none of what you said, however true, is in any way contradictory to what I said in my post. True white reflects all colors. True black reflects none. Period. I don't see what's so difficult about that simple concept.