The Mercedes-Benz 250D (W124) like all W124s came from the factory with a thick bitumen-based underbody coating. While this underseal protected the car when new, after decades it often becomes brittle, cracks, and traps moisture. This not only hides corrosion but also makes proper restoration more difficult. Sandblasting alone is not effective on the W124’s underbody because the bitumen absorbs the blasting media rather than breaking away. To expose the bare metal properly, the old coating must