leather cuirass

[Magnus]

That's actually the complete opposite of my point. Blue coloured iron is probably reflecting the sky, and green coloured iron is probably reflecting the environment. Otherwise, given that they had black and white pigments, iron would always be grey.

All blue, and all green, is a simplistic representation of the reflections in the iron. That's all. It's a simple Occam's Razor explanation for why the artist would paint grey iron as blue or green, unless iron in those days was either blue or green.

Jim, how do you know that is the reason such armours are done green and blue?