I got this one at the Martinsburg, WVA show yesterday. It was rusty-colored-dirt-soot(?)/film and I thought the green tint it had was due to that dirt. I have cleaned many insulators with this same kind of dirt/film on them and, sure enough, when they come out of the acid they are plain ol' aqua. Well, Doug (Williams), my hat is off to you! You were right, it stayed green! Its an SN 4  - neat piece - neat color!