I have several port holes on my boat that have a sticky substance on the lenses. The substance is meant to provide a sort of distortion that prevents a clear view into the cabin, sort of like a shower door. It's meant to provide privacy into the shower, vanity, and cabin area. I'd rather use the curtains for that and clean the substance off the lenses. Does anyone know whether this can be done? If so, with what product? Or woulds I need to purchase new lenses? Thanks.