Surface Contamination!

Ever take the time to fully wash and dry a car, only to notice that the clean dry paint surface feels rough???  Sometimes you can actually hear the roughness as you slide your hand back and forth across the paint surface.  What is that stuff and how do you get rid of it?  Well, you will find out in this month’s blog entry.

What is Surface Contamination?

There are all kinds of particles floating in the air around us.  Dust and pollen are the most common.  And there are many industrial contaminants as well.  For example, tiny iron particles emanate from factories, shipyards, and railroad operations; these are sometimes referred to as “ferrous oxide deposits”.  Vehicles parked near airports or under flight paths can be sprayed with tiny droplets from airplane exhaust.

And then there is paint overspray, which results from tiny paint droplets floating onto the vehicle from nearby painting operations.  If the wind is just right, these droplets can even travel all the way over to your car from the spray equipment that is being used to repaint a house several doors down!  Not to mention if you happen to park right next to a building that is being sprayed.

The vehicle can also be exposed to all kinds of contaminants just driving down the road.  Vehicle exhaust, kicked-up contaminants, and chemicals used for ice removal are just some.  Driving in wet conditions sends all kinds of junk onto the car.

Anyway, any and all of these contaminants settle onto the surface of your vehicle, and, combined with moisture like morning dew or precipitation, can adhere onto the paint.  In the case of iron particles, they can actually rust or embed into the paint surface.  On light colored vehicles, iron deposits look like very tiny brown dots on the surface.  On darker vehicles, iron deposits may have an iridescent ring around each dot.

Heavier concentrations of surface contamination can actually reduce the shine, gloss, and clarity of the paint.

Removing Surface Contamination

There are essentially four ways to reduce surface contamination:

  • Heavy buffing
  • Using detailer’s “clay”
  • Using clay media like Proje’s Clay Mitt, or
  • Using chemicals (which works only for certain contaminants).

Heavy Buffing.  Before the late 1980s, the standard method for removing surface contamination was to use a high-speed polisher with a wool pad and aggressive compound.  Along with the follow-up polishing steps needed after compounding, this process took a lot of time.  More importantly, it removed what would be considered by today’s standards, a large amount of paint.

Detailers’ Clay.  In the 1990s, a product generically referred to as “automotive detail clay” was developed by Tadao Kodate, a Japanese auto body technician.  This product revolutionized the surface contamination process for auto detailers.  The “clay”, which is actually a bar of pliable plastic resin, is rubbed gently across the paint surface using a lubricant like Proje’s Throwback Clay Lube so that it doesn’t stick.

Anything that is on the surface of the paint is “erased” by being pulled up into the clay bar.  Detail clay will not remove any sub-surface paint damage like scratches and etching.  On the other hand, unlike buffing, no paint is removed in the process (although some of the dried up paint on an oxidized single stage paint system may come off).

The only real drawback of using a bar of detail clay is that, if it is dropped on the ground accidentally, the clay bar must be discarded.  This is because the clay will grab grit from the ground, which will act like coarse sandpaper if the clay continues to be used on the vehicle.  To help reduce the impact of this mistake that all of us occasionally make, it is suggested that a new bar of clay be divided into three or four parts, and use only one of those parts at a time.  That way, if the piece of clay is dropped, one is not losing the entire bar!

Clay Media.  More recently, a new technology has been developed for removing surface contamination from vehicle paint.  Generically called “clay media”, it involves coating a towel or mitt with a thin polymerized rubber coating, which, when rubbed across the paint surface with a lubricant, causes both physical removal of the contamination, as well as a static electrical force that attracts contamination away from the surface.

The beauty of this new clay media technology is that if the device is dropped on the ground or otherwise contaminated with dirt, it can simply be rinsed off before continuing to use.  Clay media also tends to be able to treat more vehicles than a bar of clay, making it more economical as well.

Chemical Removal of Surface Contamination.  Sometimes, the surface contamination is bad enough that traditional clay methods may not work, or will simply take too long.  This is when a chemical treatment can help.

Specifically, with ferrous oxide deposits that have embedded into the paint, Proje’s Decon Iron Remover will help loosen these particles from the painted surfaces.  A clay step may still be necessary, but it will be much easier than trying to remove the iron particles with clay alone.

Clay products don’t work on tree sap either.  For this, use acetone or isopropyl alcohol to remove the tree sap globules before claying the car.

Surface Contamination Process

There are very important methodologies to follow when using detailer’s clay or clay mitts, not to mention the chemical removal processes.  We will focus on this in an upcoming blog entry.

Am I Done?

Once the surface contamination is removed to your satisfaction, the painted surfaces must be protected.  If the paint had any kind of sealant or wax on it, the Surface contamination removal process will take off this protection too, leaving the paint completely naked.  In an upcoming blog entry, we will discuss how surface contamination removal and paint protection work hand in hand.


Surface contamination is inevitable for a vehicle that spends any time outside of a garage.  Removal of surface contamination is important before applying sealant, wax, or ceramic coating.  Stay tuned for more discussion of these important processes.