Autos: scraping rust from the undercarriage

Self-tutoring about car care: the tutor mentions scraping rust from underneath a car.

Prepping the undercarriage of one of the vehicles for rust treatment (home-style), I wanted to do so without damaging anything. Wire brushes can be used on some big, non-sensitive areas, but what about small, oddly-shaped places or ones near wires, etc? Preferable would be something gritty, yet gentler and more flexible than a wire brush.

I used several tools: steel wool, sandpaper, and even a heavy-duty scrub sponge – the kind with a soft side and an abrasive side. The scrub sponge – specifically, the abrasive side – proved surprisingly useful.