Oxidation

Oxidation, (Redox (reduction–oxidation)) is a process in which a chemical substance degrades in the presence of oxygen/ozone or other oxidizing agents. When this happens to metals, we call it 'rust', however it will also happen to plastics, rubbers and paintwork. In the context of car paint, oxidation can occur when the paint is exposed to oxygen and ultraviolet (UV) light. This can result in the loss of electrons from the material, which can weaken and damage it over time.

When it occurs on paintwork, the surface of the paint will become dull and may appear hazy, milky and flat, on very oxidized paintwork, it may even appear powdery. This 'dead paint' is fairly easy to remove with even hand polishing, as oxidized paint is usually soft.

It can be prevented by coating your paintwork with wax, which seals the paint against oxygen and will become oxidized instead (a sacrificial layer). Speciality coatings such as ceramic are more resistant to oxidization.

What it means

Oxidation is what happens when paint and plastics are slowly broken down by oxygen, UV light and general weathering. On paint, the top layer dries out and becomes porous, so the surface turns dull, loses depth of colour and can feel chalky or dusty when you rub it. On older single-stage paints the colour itself goes flat and powdery, while on clearcoated cars you tend to see haziness, loss of gloss and, in later stages, clearcoat failure where it starts to peel or flake.

Why it matters

• Ruins the look of the car: Oxidised paint and trims make a car look older and neglected, even if the underlying panels are straight and undamaged.
• Signals surface breakdown: Once the surface layer has oxidised it is more open to moisture and contamination, which can speed up further deterioration.
• Limits what polishing can achieve: Light to moderate oxidation can often be improved with machine polishing, but heavy oxidation and peeling clearcoat cannot be polished back to new and usually need repainting.
• Shows the value of protection: Areas that have been waxed, coated or kept out of the sun usually oxidise far less than exposed panels, which is why protection and storage make such a difference over a few years.

Where you’ll see it

You will see oxidation mentioned on detailing estimates, inspection reports and bodyshop appraisals, especially on older cars, neglected daily drivers and vehicles that live outside. Typical phrases include dull, oxidised paint, chalky paint, faded red or pinking paint and early clearcoat failure on bonnets and roofs.

Context

Oxidation sits alongside things like industrial fallout, wash marring and bird-lime etching as common paint problems. Detailers often carry out a test spot with compound and machine polish to see how much of the oxidised layer can be safely removed and how much gloss can be recovered. Light oxidation on sound clearcoat is usually treatable with polishing and then protection. Advanced oxidation, where the clearcoat has turned milky, crazed or is peeling, is past the point of correction and moves into the territory of repaint rather than detailing.

Common mistakes

• Expecting heavy, chalky or peeling paint to be restored fully by polishing when the clearcoat has already failed and really needs repainting.
• Using very aggressive compounds or sandpaper on thin, oxidised paint without checking thickness, which can quickly cut through to primer or metal.
• Polishing oxidised paint back to a shine and then skipping wax or coating, so the freshly exposed layer oxidises again quite quickly.
• Confusing oxidation with contamination such as traffic film or fallout and repeatedly washing with strong chemicals instead of tackling the root cause.

Written by Danny Argent. Last updated 19/11/2025 15:22