All three insulators had the same hazy patina that could not be removed with oxalic acid. The yellow olive green Star signal and plum California signal were then hand buffed with a rag and a tin oxide paste that I mixed with tin oxide powder and water and applied with an old toothbrush. Rinse and repeat procedure as many times as needed to achieve your desired result. Mine took 1 or 2 applications per insulator. Tin oxide is commercially available and used to polish granite and marble. It is a less toxic alternative that doesn't leave a residue on the glass that would happen with an oil or spray coating . The hazy film was pretty superficial. and I was told this polishing agent will not work on a deeply pitted insulator.

Note: This technique does not remove glass damage. Glass damage obscured by the hazy patina will become much more apparent once the haziness is removed.

Note: I tried this polish on a piece with a visible-to-the-naked-eye scratch patch on the glass. The tin oxide could not remove the scratches, so this manual method has its limitations.