Does all zinc based parkerizing eventually turn colors from a medium gray to a gray-green? I've bought a few used parts lately for my 03A1 and found that the parkerizing is a medium gray. My understanding is that it takes about two years for the green tint to appear on the parkerizing. However, I'm not sure now if new zinc based parkerizing processes have been developed which prevent the gray from turning gray-green. I like the gray green better and suspect that these 03A1 parts I purchased do not have their original finish and have instead been reparkerized within the last couple of years.

Also am wondering what causes the gray-green color??? I've assumed it's from the phosphoric acid based on the green color of the OS-PHO brand phosphoric acid I buy at Ace Hardware to kill rust.

Any thoughts??? Thanks!