I don’t claim to be an expert on paint. Or color. I am able to use Google and here are some interesting resources you may wish to take a glance at.
The Yellowing of White Paint from The Painter and Decorator 1917
Automobile Paint Resin from Chemical Criminalistics (Text Book)
I’m listing this stuff because it’s interesting and it also illustrates several points I try to make on forums before some jackass shows up and becomes abusive. Paint chemistry is not only complex, it has changed greatly since 1917. Aircraft paints made in 1940 were made by 1940 people, not 2017 people who know things that 1940 people did not know.
The lack of knowledge is often the single greatest contributor to some kind of failure in the paint or the failure to understand how the paint might fail. Paint failure can result from not knowing or understanding something in the wrong way. What you don’t know CAN hurt you. So, again, when we try to paste our understanding from 2017 onto the paint lab at Mitsubishi in 1940 we are doing something stupid. It does not matter what the chemistry tells us now. If they didn’t know it back then, then it may show up accidentally or for some specious reason or it may not.
I don’t know what color Zeroes were painted in 1940 or 41 or whatever. I don’t know how Mitsubishi mixed up their paint, and neither does anybody else. What I mean by that is that measuring relics, or trying to reconstruct paint colors from documents taken out of context, or using a chain of reasoning from the year 2017 is hopeless. You won’t get there that way because no matter how much you think you have the truth, you will probably just have a pretty good guess. Not absolute knowledge. Just an approximation.
The difference between “knowing” and “guessing” involves the fact that we don’t know how they did things back then. There are too many missing elements to be certain that we have it right. The past fades over time, and it fades into a blur that we cannot penetrate. Technologies change over time in ways that obliterate certain other technologies.
How many people today can identify a hand crank on a car? How many could hand start a car? Imagine someone who had never seen a car hand started trying to explain certain types of arm fractures seen in the 1920’s. The lack of understanding of the car starting crank would lead them to assign other explanations to the broken arms other than the correct one (a failure to disengage the starter crank causing the crank to whip around and break the arm). It would be easy to jump to the conclusion that people’s arms were broken because of falls from horses, an exactly wrong hypothesis.
We will never know what color Japanese Zeroes were painted–precisely. All we have is approximation. We are simply missing too much information to make even a “really good” guess on what that color would have “looked like.”