Making the automotive paint surface look great is one of the most common activities of the professional detailer. It is important, then, that the technician be able to evaluate and diagnose common paint problems and offer solutions to the customer. Commonly found paint problems fall into two categories. There can be contamination on the surface, or there is damage that goes into the paint layers. In this month’s column, we are going to focus on surface paint problems.
Surface paint problems include environmental fallout, ferrous oxide deposits (rail dust), paint overspray, bug and tar splatters, cement splatters, and water spots.
Environmental fallout is a generic term that refers to all of the particulate crud that is floating around in the air. This stuff settles down onto the paint surface as the vehicle sits outside in the open air. This can be stuff like grime, sticky 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 fallout by itself is not a problem for the paint, but when combined with water from precipitation or dew, the environmental fallout can become fused with the surface of the paint.
Ferrous 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 to the ferrous oxide particles that come from railroads. As the trains run 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.
Ferrous 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 or rainbow-like ring.
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 hard water. As the water dries, the minerals settle onto the paint surface, leaving rings the size of the original water drops. Water spots may also occur when precipitation falls on a vehicle that is already covered in dry contamination like dust or construction-related powder.
All of these surface contaminants cause the paint surface to feel rough, even after washing and waxing. The remedy for minor surface contamination is to use detailing clay or clay media devices.
Heavy Surface Contamination
Heavier concentrations of surface contamination may require an added wash step involving the use of a special chemical to help loosen the fallout. Currently, there are three options of chemical treatments commonly used for removal of excess surface contamination: alkaline pre-wash, acid pre-wash, and sulfur-based iron remover.
Alkaline pre-wash. This product, which is highly alkaline (e.g., pH of around 12.0), is sprayed onto a pre-rinsed vehicle to loosen heavy grime, build-up, and surface contaminants before performing a standard contact wash. It targets organic contaminants like oil, grease, road film, and oily grime. This extra step is indicated for vehicles that have been neglected for years or that have been through special circumstances.
Alkaline pre-washing is especially recommended for annual cleaning (de-clogging) and coating booster service for vehicles that have received a professionally applied ceramic coating service. Full disclosure: I am not a fan of the term “clogging” because it implies some kind of porosity. Since one of the main benefits of a ceramic coating is that it provides a non-porous and impenetrable surface, it is a bit silly to suggest that it can become “clogged.”
Instead, what is really happening is that, over time, the coating is covered with a layer of film build-up that does not come off with normal washing. The impact of that film is that the vehicle paint is not as shiny and glossy as it was right after the ceramic was applied. Fortunately, a good pre-wash and ceramic booster will typically remedy this.
Acid pre-wash. This type of product usually contains oxalic acid (pH 2-3.5) or phosphoric acid (pH 2-3). This treatment is indicated for vehicles suffering from inorganic contamination like heavy iron oxide deposits, water spots, and build-up of road film from deicing salts. Note that only products designed specifically for automotive acid washing should be used. Never use products containing hydrofluoric acid on the vehicle body. It is not safe for many of the surfaces and is dangerous for the user. Also, do not use your favorite acidic wheel cleaner for this purpose.
The acid wash product is sprayed or foamed onto the vehicle surface and allowed to dwell for a few minutes. As it does, mineral deposits are dissolved and embedded iron particles are loosened. The removal of mineral deposits may be aided by agitation. However, when attacking iron particles specifically, it is best to simply rinse the acid wash off the vehicle after the prescribed dwell time; then, the later clay procedure will be much easier.
Acid washing is a specialized procedure that should be performed only by trained professionals. The procedure involves a number of important steps, including an initial wash of the vehicle using normal car wash shampoo, to remove loose dirt and grime. Next, the formal acid washing step occurs with a dedicated bucket and wash mitt to be used with the fallout. After rinsing off the acid wash residue, the vehicle is washed once more with a neutralizing solution, using a dedicated wash mitt and a stronger concentration of wash shampoo or even a mild all-purpose cleaner solution.
Iron removers. A new class of automotive cleaning product came out around 2010, touted as an acid wash substitute using a sulfur-based compound to loosen iron particles. Once sprayed onto the affected area, the product is attracted to iron particles, bonding directly with them. By accelerating the oxidation process, the product dissolves the jagged edges of the particle, breaking the bond with the vehicle surface, and creating a more rounded shape that is water soluble and easier to remove with simple rinsing. The added bonus in using these products is the dramatic appearance of reddish-purple residue resulting from the chemical reaction.
The Clay Step
Regardless of which pre-wash treatment is chosen, if it’s even necessary, the next step is to perform a contact wash with your favorite pH neutral high-foaming standard car shampoo. Then the car is fully rinsed. It is now ready for clay treatment to remove any remaining surface contamination.
The clay treatment removes the roughness that remains after normal washing. Most customers who have washed their own cars have experienced the remaining roughness resulting from surface contamination, so it is easy to explain the importance of the surface contamination step.
The clay bar. In the very old days, the only way to remove surface contamination was with aggressive buffing, which also removed some of the paint thickness, and was quite time-consuming. The need for this arduous step was virtually eliminated by the invention of “detail clay,” which was introduced in the United States in the early 1990s.
The product is actually a malleable bar of plastic resin that resembles the look and feel of clay. A piece of the clay bar is kneaded into a pancake shape and rubbed across the paint surface using a lubricant like mist-and-wipe spray wax or even car wash shampoo solution. As the clay bar moves across the surface, it grabs anything that is stuck to the paint. Claying an entire vehicle using proper technique can take up to 30 minutes or longer.
One challenge with clay bars is that they must be discarded if dropped on the ground because the clay will pick up grit that will scratch the vehicle if used again. That’s why we typically recommend using only one third of a new clay bar at a time — if it’s dropped, you’re only throwing away a third of the bar.
Clay media. In the early 2010s, a new type of surface contamination device was introduced, the “clay mitt” or “clay towel.” A form of polymerized rubber is sprayed onto an application device like a microfiber towel, mitt, or hand-held block. The technique is like that of using clay bar — rub the device across the paint surface after spraying down a lubricant.
One particularly useful clay media device is the “clay disk,” which is the same polymerized rubber placed onto a 3”, 5”, or 6” foam disk for use with a random-orbit polisher. This method takes quite a bit less time than claying a car by hand using bar clay or clay media. Most technicians find it necessary to follow up by spot-claying certain vehicle contours that the clay disk cannot reach.
There are several advantages to clay media over bar clay. First, if you drop a clay towel, you simply rinse it off and keep using it. Second, a properly maintained clay media device will last longer than a bar of clay. The bar clay collects the surface contaminants and eventually becomes too “contaminated” to use without scratching. Clay media, on the other hand, does not hold onto contaminants, which can be rinsed off during and after every use.
Some technicians find that clay media is not quite as thorough in contamination removal as traditional bar clay. Others find that bar clay is better at removing stubborn contamination. So, we keep bar clay on hand for those tougher jobs.
Summary
The detail industry has come a long way from the days of using a rotary polisher with a wool pad and compound to remove surface contamination from automotive paint. Detailer’s clay virtually eliminated the need for this old-school method. Clay media devices have gone a long way to making the clay step even easier. And decontamination pre-wash chemicals help even more. Today, paint surface contamination is an automatic but very simple part of making a car look beautiful.
Prentice St. Clair, CD-SV/RIT, has been serving the automotive reconditioning industry since 1999 with impassioned consulting and training and the goal of increasing the profitability of the automotive detailing and reconditioning industry. He is proud to have been inducted into the International Detailing Association’s Hall of Fame. Prentice welcomes inquiries that lead to the opportunity to help readers achieve excellent results. He can be reached via call or text at (619) 701-1100 or e-mail at prentice@detailingprogress.com.