Rusty vintage Rolex: how to cure 'under the crystal' rust?

 

If you are into vintage Rolex submariners fitted with plexi glass (models 5513 and 1680) then you are well aware of a rather annoying problem-  rust visible 'through' plastic glass. This unsightly imperfection is actually too common; finding a perfect vintage Rolex submariner showing no sign of rust and pitting underneath the bezel is almost impossible. Pitting is a form of extremely localised galvanic corrosion that leads to the creation of small holes in the metal. Actually, even the smallest amount of rust located directly underneath the crystal is perfectly visible, thanks to glass acting as a magnifying lens. The only way to get rid of the rust is to remove the bezel, bezel tension ring and then the plexiglass itself and clean all pitted surfaces.

Here is a photo of the middle case after rust removal. Unfortunately the pitted case is no longer waterproof. The possible solution to restore water resistance would be to grind out pitted spots, fill in the cavity by laser welding and then re-grind the surface. However this intervention is a rather major undertaking and would only be done with the owners approval only.