I took this picture for Colin and the other mud hogs. Perhaps they can tell me what I'm looking at. From back in my ceramics days, I know the brown glaze is called Albany Slip, widely used in industrial ceramics. It is a very low firing clay mined in Albany, New York. The powdered clay is mixed into a paste, and the ceramic piece is dipped, to obtain a even, thin coat, before being high fired, where it melts into a glaze. Many variations of color can be achieved by adding metal oxides and / or fluxes to the slip. Note the metallic sheen on the small insulator. Better viewed if you enlarge the picture. Photo taken with Nikon D70 -- 210 mm lens.