Rustproofing

In traditional automotive manufacturing of the early- and mid-20th century, paint was the final part of the rustproofing barrier between the body shell and the atmosphere, except on the underside.

The coating chemistry is waterborne enamel based on epoxy, an aminoalcohol adduct, and blocked isocyanate, which all crosslink on baking to form an epoxy-urethane resin system.

For modern automobile manufacturing after the 1990s, nearly all cars use e-coat technology as base foundation for their corrosion protection coating system.

[1] Aftermarket kits are available to apply rustproofing compounds both to external surfaces and inside enclosed sections, for example sills/rocker panels (see monocoque), through either existing or specially drilled holes.

The hardening and drying products are also known as "Shutz" and "Anti Stone Chip" with similar potential problems to the original factory underseals.

[3] There are many manufacturers of similar products at varying prices, these are regularly group tested and reviewed in the classic car magazine press.

[citation needed] Additionally, a petroleum, solvent-free rust inhibitor remains on the metal surface, sealing it from rust-accelerating water and oxygen.

Other benefits of petroleum-based rust protection include the self-healing properties that come naturally to oils, which helps undercoatings to resist abrasion caused by road sand and other debris.

The disadvantage of using a petroleum-based coating is the film left over on surfaces, rendering these products too messy for top side exterior application, and unsafe in areas where it can be slipped on.

[4] However, there is no peer reviewed scientific testing and validation supporting the use of these devices and corrosion control professionals find they do not work.

Pierre Berthier, a Frenchman, was the first to notice the rust-resistant properties of mixing chromium with alloys in 1821, which led to new metal treating and metallurgy processes, and eventually the creation of usable stainless steel.