[xyzzy123]

Great discussion on colour theory but I think it skips over the fact that chemistry and economics were also real constraints. Paints that don't fade easily, chemically inert, durable etc and can be produced in enormous volume are not that common. Practical stuff like, how easy does it catch fire, do solvents degrade it. Most important: is it CHEAP?

Also by 1944 there would have been a ready made supply chain due to demand from the navy, which would have picked it for similar reasons and consumed it in enormous volume.

I think, practically, control rooms are chrome oxide green (you get to add as much titanium as you like - thats cheap as dirt too EDIT: it would have been lead actually in the 40s) for much the same reason that barns are red.

[justonceokay]

I doubt the manhattan project had an issue funding paint

[xyzzy123]

Think for a minute about why they worked in shacks.

Also worth noting that Birren was a paid consultant for DuPont - the company that made the paint. From that perspective alone you would kinda expect he is gonna pick colours they already produce reliably at scale.

He also consulted for army, coast guard and navy so whatever colours you pick for hazard marking in an industrial setting have to be _vaguely_ congruent or you're going to cause accidents.