POF No4 in green

[Bruce_in_Oz]

Good hint about the cosmoline source.

Was it all the SAME colour, or like automotive greases, did it come in various shades from different sub-contractors?

Parkerising will absorb some of whatever it is coated with. That is its intended function; to hold oil or grease which are really the things that repel water and prevent rust.

If you had been parkerised properly and stuffed into a box of green grease for sixty years, I doubt you would retain your original palour.