Steel variation

[Breck Gorman]

Here is a pattern on a Parker that seems to have two different types of steel, and colors differently when refinished. I’ve seen this on other barrels, but this on was really pronounced
My theory (and I would love to hear others) is that the riband was composed of three different billet metals:
1 a high carbon steel that reacts with oxidation and logwood to color black
2 a low carbon steel that doesn’t react as strongly and colors grey
2 very low carbon and corrosion resistant wrought iron that colors white.

If this sort of thing fascinates me, does that make me eccentric?