The "black stuff" is what is left behind after Naval Jelly is left on the fenders for 37 years. There is what also appears as calcium/salt deposits built up in spots on the car from perhaps the salt air. These are a problem because at the end of the white deposits the base has eaten to the metal. Not bad, but it has killed the paint. The black stuff seams to dissolve and friend was over yesterday and was fasinated with the car. He suggested 'gojo' hand cleaner so we smeared some around and it breaks up the "black stuff". We are just cleaning up the car in areas for SCRX. We removed the carpets, etc yesterday for cleaning. The floor pans and underlay look like they were installed last week....BKH