In the July issue of Auto Laundry News, I started a series on the treatment of automotive paint, first spending time describing common paint problems, which fall into two categories. In Part I, I discussed the first of these categories: contamination on the surface. In this Part II, we’ll take a closer look at damage that goes into the paint layers.
SUB-SURFACE PAINT PROBLEMS
Sub-surface paint problems occur when the damage goes below the surface of the paint. Such damage includes oxidation, scratches, chips, staining, and etching.
Oxidation is a condition of automotive paint in which certain chemical substances within the finish attach to oxygen molecules in the air over time, causing the paint surface to become dry, dull, and sometimes “chalky.” Put more simply, it is the drying out of the paint. Paint starts out as a liquid that is sprayed onto the car. The paint quickly dries to the point that it feels “solid.” But the paint never stops drying out.
The liquids that made up the paint before it was sprayed onto the car continue to evaporate, albeit at a slower and slower rate, over time. Without regular waxing, and after many years or heavy exposure to heat and sunlight, the paint will dry to the point that it becomes dull.
In single stage paint systems, oxidation can be mostly removed by compounding or polishing the paint surface, which removes the “dead” paint. On clearcoat paint systems, oxidation appears as cloudiness in the clearcoat (not the basecoat!). Unfortunately, clearcoat oxidation begins deeper in the paint and is virtually impossible to remove. Typically, the detailing chemicals and specific buffing procedures used will differ depending on which kind of paint system is oxidized.
Another paint problem that is caused by age is paint cracking. Sometimes called “checking” or “crazing,” it is caused when the layers of paint expand and contract at different rates, causing the top layer of paint to split or crack. These small cracks appear similar to a dry lake bed on the surface of the paint, in a random, multi-directional pattern. They can be quite deep into the paint surface and are generally not able to be fixed with standard detailing techniques.
Scratches are essentially small gouges into the paint. Scratches can fall into one of three categories: micro-scratches, moderate scratches, and deep scratches.
Micro-scratches are super fine scratches caused by light contact like normal washing. These types of scratches, which some people call “cob-web” or “spider webbing,” are typically only visible in sunlight.
Swirl marks are another form of micro-scratches that are caused by aggressive buffing with a simple rotary (high-speed) buffer while using abrasive cleaners or compounds. For this reason, they can be considered “technical” micro-scratches because they are caused by the detailing technician. Swirl marks appear to be in the shape of circular arcs while non-technical micro-scratches have a much more random pattern. All types of micro-scratches can typically be removed with light polishing, for example by using a swirl-removing polish and a foam polishing pad.
Holograms are simply a form of swirl mark. They are called such because they appear to be three-dimensional and appear to go “deep” into the paint (even though they are just on the surface) as one views the paint while walking around the damaged area.
Moderate scratches are those that can be removed or at least made to look less noticeable. These are often caused by incidental contact with the paint, like rubbing up against a side panel with a gym bag or sliding a box onto the trunk. Deep scratches are those that are down to the basecoat or primer. Unfortunately, these cannot be removed, nor can they be made to look less noticeable using standard detailing techniques.
Other sub-surface problems include staining and etching, which can be caused by acid rain, bird droppings, and engine fluids. Etching is when the surface contaminant eats away at the paint. Bird droppings and eggs are famous for this. It is difficult to repair etching, especially if it is deep into the paint. Acid rain is natural precipitation contaminated with acidic compounds from industrial pollution. It can cause damage like etching or discoloration of automotive finishes and glass. The best solution is prevention — educate your customers on the importance of regular waxing or sealant application.
Paint chips or nicks are caused by sharp impacts like rocks or keys or other car doors. Some nicks can be improved using remedies similar to those used for scratches. Chipped-off paint, however, cannot be improved using standard detailing techniques. Instead, professional touch-up paint techniques can be used to fill in the chip, making it less noticeable.
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 firstname.lastname@example.org.