I’ve had a few all-cotton black shirts in my day (Polo knit, plain old t-shirts…). I notice that as they fade, they turn not to grey, but a REALLY DARK green. Are black and green dyes related?
I’ll just toss in this anecdotal observation; There is no true black in nature, since by definition black is the absence of light. In Art class clever teachers often take away all the black paint and force their students to see the colors in the blackness. I suspect that for a shirt manufacturer (or ink jet cartridge consuming device) to get a black they have to decide upon a particular color to make really dark.
It’s obviously Ralph Lauren’s wry comment on radical environmentialism.