Defender, Discovery, Motorhome – Before n After rustproofing

Classification: c) Over 10 years old but very clean for age. Not expected to need re-treatment under the guarantee.
It's impossible to know the real state of the underbody because it has been schutzed. (Schutz is the German word for protection. In this case it's a plastic coating). The question is: "when was the schutz applied?" If if was applied early in the car's life onto clean metal we're good. If it was applied over rust then my coating will only be as good as the schutz which is not good because while schutz will hold the rust down well for a year or two, it has no anti-corrosive ingredients.. So if rust starts to come through the schutz, what do you do? If you pressure wash it, some of the schutz may be removed to reveal rust festering underneath but how much rust is still there festering away, ready to break through in another year or two? Impossible to know. Whereas with my coatings, if the faii in places they can be pressure washed and a new application will soak into the prior application, rejuvenate it. and form an amalgam with it.