Here is a string of 9 inch gray PINCO suspensions with a flash mark all the way down the entire length of the string (the black burn lines) These units are not very old as they were installed in 1978. The area is surrounded by trees and has a tendency to become swampy, so the insulators could of become contaminated by fog dispersed contaminants. Gray glazed insulators make damaged units more easy to detect as this picture is proof of.