The car came to us mid-restoration, up on a hoist, with a hard constraint: the owner wanted the underside presentable for inspection without pulling the subframes, without soaking the shell, and without putting a wire wheel anywhere near original factory markings.
That rules out almost every conventional option. Pressure washing drives water into seams and box sections and leaves you chasing corrosion for months. Chemical degreasers strip the underseal along with the grime, and the run-off has to go somewhere. Abrasive media buries itself in every cavity and turns up in the diff oil two years later.
Dry ice sublimates. It hits the surface at −78 °C, shocks the contaminant layer loose, and turns straight back into gas. The only thing left on the floor is the dirt that came off the car.
Strip decades of road film and oil mist from the full underbody, in situ, on the hoist.
Preserve sound underseal, factory paint marks, inspection stamps and cavity wax.
Keep water out of every seam, box section and electrical connector.
Leave a surface the restorer can inspect, photograph and weld to immediately.
