Decontamination is the step between washing and protecting, and it is the one most people have never heard of. A wash removes loose dirt. Decontamination removes what has chemically or mechanically bonded to the paint: iron particles from brake dust and rail traffic, mineral deposits from hard water and sprinklers, road film, tree sap and bug residue that has etched into the surface.
You can feel the difference with your hand. Washed paint that still feels gritty is contaminated paint, and any wax, sealant or coating applied to it will bond poorly and fail early.
Chemical decontamination
An iron-dissolving product is applied to the paint and wheels and allowed to dwell. It reacts with embedded ferrous particles and breaks them down so they can be rinsed away. This step is particularly worthwhile on vehicles that commute regularly, since brake dust is the main source, and on light-colored paint where iron fallout shows as small rust-colored specks.
A separate mineral-focused treatment addresses the calcium and magnesium deposits that hard water and sprinkler overspray leave behind, which is a much bigger factor in this valley than in most markets.
Mechanical decontamination
What chemistry cannot dissolve gets sheared off mechanically with a clay bar or clay medium and plenty of lubrication. This physically removes bonded particles sitting proud of the clear coat and leaves the surface glass smooth.
When decontamination is needed
- The paint feels rough after washing and drying
- Small rust-colored specks appear on light-colored panels
- Water no longer beads the way it used to
- The vehicle is being prepared for a sealant or ceramic coating
- The vehicle has been parked near sprinklers or construction
What it will not do
Decontamination removes what sits on the paint. It does not remove defects that are in the paint. Swirl marks, haze and etched water spots remain afterwards, and those require polishing. Decontamination often makes them more visible, simply because the surface is finally clean enough to see clearly.
Frequently asked questions
- Does clay damage paint?
- Not when used with adequate lubrication and clean media. Clay used dry or dropped on the ground and reused is what causes marring, which is why the medium is replaced when it is contaminated.
- How often does paint need decontamination?
- Only when the surface tells you it does. Use the bag test after a wash: if the paint feels rough, it is due. Most well-maintained vehicles here need it once or twice a year.
- Is decontamination included in a full detail?
- It is included when the paint condition calls for it. On a maintained vehicle where the surface is already smooth, it would be unnecessary work.