In this month’s column, I will start a series on the treatment of automotive paint, first spending time describing common paint problems, which fall into two categories. There can be contamination on the surface, and there can be damage that goes into the paint layers, a condition we will discuss in detail next month.


Surface paint problems include environmental fallout, ferrous oxide deposits (rail dust), paint overspray, bug and tar splatters, cement splatters, road grime, and water spots.

“Environmental fallout” is a generic term that refers to the particulate crud that is floating around in the air. This stuff settles down onto the paint surface of the vehicle as it sits outside in the open air. Things like pollen, volcanic dust, jet fuel, paint droplets, industrial particulates (e.g., sanding and grinding debris), and any number of atomized chemicals released from industrial operations.

Most of this stuff by itself is not a problem for the paint, but when combined with water from precipitation or dew, most environmental fallout becomes fused with the surface of the paint.

Sometimes, the result is water spots, which are mineral deposits on the surface of the paint. In the extreme case, like acid rain, the fallout and water combination actually etches into the paint, creating a sub-surface problem (more about this later). It is difficult to distinguish between water spots and water etching until the technician actually works on the area with detailer’s clay or compound.

Water Spots are left on the surface when water droplets are allowed to dry on the vehicle’s surface. The spotting is caused by leftover minerals and other solids that are contained in most tap water. As the water dries, the minerals settle onto the paint surface, leaving rings the size of the original water drops.

One common source of water spots is errant irrigation sprinklers that splash the side of the car when it is parked next to a lawn or other landscaping. Another common source is automatic car washes that do not adequately dry off all rinse water, leaving droplets on the paint as the vehicle exits the wash tunnel.

Natural rain by itself does not cause heavy water spotting, but if there are a lot of particulates in the air — either man-made or natural — the rain will collect these onto the paint surface. Once the rain droplets dry, the particulates remain as an outline of the rain droplet.

Paint Overspray, which is tiny droplets of atomized substances such as paint mist that settles out of the air onto automobile surfaces appearing as tiny speckles, also sticks to the paint. Most overspray can be removed using detailer’s clay, but sometimes wet-sanding and buffing are necessary.

Iron oxide deposits are a specific form of environmental fallout that are made up of tiny iron particles that come from industrial operations. You may have heard the term “rail dust,” which refers specifically to the ferrous oxide particles that come from railroads. As the trains runs along the rails, the contact and friction between the steel wheels on the train cars and the iron rails causes small, almost microscopic pieces of iron to spit out and float away in the air.

Iron oxide particles can also come from other metal-working industries such as ship-making. They appear as small brown nibs on the surface of the paint.

Sometimes, especially on white vehicles, there is a brown ring surrounding the particle. The total width of the ring is less than 1/32 of an inch wide. On darker vehicles, the iron particle might be surrounded by an iridescent ring.

Most technicians default to using detailer’s clay to remove iron oxide particles, but sometimes a portion of the particle can remain imbedded in the paint, requiring more aggressive cleaning techniques like acid washing or use of sulfur-based iron removing chemicals. These two methods essentially loosen the iron particle from its embedded spot, allowing easier removal via standard washing or using detailer’s clay.

Another surface paint problem is “orange peel,” the nubby rough appearance of paint that looks much like the texture of the skin of an orange or other citrus fruit. It is an artifact of the painting process (the sprayed-on paint rarely levels perfectly) and can cause the paint surface to be less reflective. Orange peel can only be removed by wet-sanding (sometimes known as “color sanding”).

Cement splatters are difficult to remove. The best way I have found is to first spray the cement with a citrus oil-based cleaner. The cleaner will partially penetrate the cement and help to loosen it. Use a plastic spatula or your fingernail to gently scratch off the cement. The oil in the cleaner will lubricate the paint surface, helping to reduce scratching. Unfortunately, some scratching of the paint is inevitable. So, it’s necessary to polish the area after the cement has been removed. There are specialty chemicals that help loosen cement splatters, and these typically require multiple applications to fully remove the splatter.

Removing bugs and tar can be accomplished with one of the many chemicals designed just for these contaminants. If the contamination is light, simply pour the chemical on a towel and wipe the affected area. If the contamination is heavier, it may be necessary to use a non-scratching scrub sponge to help agitate away the tar or bugs. Always apply wax to the cleaned area, as most of these chemicals will remove any existing wax.


There are many ways that paint can become damaged. Often there are several types of damage that, combined, cause the paint to look dull and old.

Understanding the types of damage, and then using the correct chemical, equipment, and technique to correct the damage, you can go a long way to making most cars look great.

Prentice St. Clair is an International Detailing Association Recognized Trainer and Certified Detailer. As the president of Detail in Progress Inc., he has been providing training and consulting to car washes and detail shops since 1999. He is available at (619) 701-1100 or