Originally Posted By: Dana
5. Each was painted battleship gray. It was hoped this would make them unobtrusive and (this is my guess) plain enough to discourage pilfering.

Mostly to be visually unobtrusive. Pilfering was discouraged more because they are relatively soft compared to chrome-molly and tended to conform to the crack and allowed crystals to dig into the metal - basically they were a bitch to remove; much more difficult than the normal harder steel pitons.