High-Tech Paint — Much Ado about Nothing
By Prentice St. Clair
I was asked to make a presentation during the educational sessions offered by the Western Carwash Association during their annual convention, which took place October 7-9 in Las Vegas. The topic was “High-Tech Paint Finishes,” and the talk was well-attended and well-received. I thought it might be a good idea to share a written summary of the presentation to those in the industry who could not attend. The full-day detailing seminar was superlative, and I strongly recommend that detailers or car wash owners with detailing centers make plans to attend next year’s WCA convention, to be held September 22-24, 2008.
First of all, be aware that a write-up on the topic of automotive paint technology could easily take up this entire magazine, so I will be brief. Second, I am going to focus on Original Equipment Manufacturer’s (OEM) processes, upon which, by far, most of us are working.
Automotive paint is typically composed of a finely ground powder, called pigment, that is mixed into a liquid resin (plastic). It is then “thinned” with solvents so that the paint can be transferred onto the automotive surface through a spray gun. There are several other additives that can be mixed into the paint for various purposes, but for our discussion are not important.
The primary purpose of automotive paint has long been to protect the sheet metal from rusting. Of course, through the years, the paint finish has taken on a critical secondary purpose of beautifying the exterior of the vehicle. The paint on an automobile is often referred to as a paint system, because it is actually a set of multiple layers of different types of coating that are designed chemically to work together to help the paint adhere to the vehicle surface and perform its primary function of protection.
To understand paint technology, let’s start with the basics. It begins with the surface upon which the paint is applied, which has been, for many decades, typically sheet metal (steel). The surface to be painted is technically known as the substrate, and these days, there are many materials other than steel used as substrate. For example, most vehicles have plastic bumper covers that are sprayed the same color as the rest of the vehicle. Some makes, like Saturn, also use plastic as the substrate for other panels like fenders and doors.
Aluminum can also be used as a substrate. I have personally seen several Ford models and also Mazda Miatas with aluminum hoods, presumably for reduced vehicle weight. Fiberglass can also be used, as in Corvettes and the rear fenders of some pick-ups. Not to mention carbon fiber and perhaps some other materials of which I am not aware.
The substrate material is coated with several layers of different paint material that is designed to fill in minor imperfections in the surface, seal the surface, and prepare the surface to receive the colored paint. There are all kinds of fancy terminology for these layers, including “zinc coating,” “cathodic electro-coat,” “E-coat,” “sealer-surfacers,” and “stone chip primer.”
I believe all that is necessary for our understanding of paint technology is to think of these various coatings as undercoats. I refer to these as “undercoats” because they go on top of the substrate but underneath the primary paint coating that makes the car look nice. Ultimately, the purpose of the undercoats is to make the paint stick.
CURRENT PAINT TECHNOLOGY
Up until the 1980s, most vehicles were coated with multiple layers of colored paint, applied to the top of the cured undercoats. So, a red car would be painted with several layers of red paint. This type of paint system is referred to by many names, including single stage or monocoat (only one type of paint being applied), or conventional (the “normal” way of painting cars for so many decades).
Although most manufacturers have since switched to the clear coat systems described below, you can still find some vehicles painted with single-stage systems. Examples include some late model Toyotas (white) and Fords (white).
Since the late 1980s and early 1990s, most manufacturers are using a base-coat/clear-coat or two-stage paint system. The color of the car is achieved by spraying a thin layer of colored paint onto the undercoats. This thin coat is known as the base coat. On top of the base coat is sprayed two or more layers of clear, non-pigmented paint. Hence the name clear coat.
So, back to our example of a red car, a thin layer of red paint is sprayed on top of the undercoats, allowed to dry, after which a couple of coats of clear paint are sprayed on top. The clear coat gives the paint a deep, glossy appearance that is generally superior to single-stage coatings.
Depending on who you ask, there are a number of reasons why manufacturers switched to base-coat/clear-coat systems, including lower cost, lower VOCs, better finish, ease of maintenance, and durability. It is not important for us as detailers to understand why clear coats are used, but how to properly maintain them.
A third type of paint system commonly used by OEM factories is the three-stage or tri-coat system. This is actually very similar to the base-coat/clear-coat system, except that an intermediate layer of paint is sprayed between the base coat and the clear top coat.
This middle layer, known as mid-coat, is typically clear paint with some special effect added, like pearlescent particles, micas, metallic flakes, or iridescent tint. It is the addition of the mid-coat that creates pearl and iridescent special effects seen in some OEM paint jobs.
Tell the Difference
Interestingly, the last two systems just described, the base-coat/clear-coat and the three-stage, both have at the outermost layer, clear paint. As detailers, we are concerned solely with what is at
the surface of the paint, which, for all intents and purposes, is going to be either single-stage paint or clear coat.
So how do you tell the difference? Well, if there is obvious dullness on the paint surface, it is likely that you are dealing with a single stage paint system, which, when oxidized, become “chalky” at the surface. If you wipe this chalky paint with a cloth moistened with wax or polish, the color of the car comes off on the cloth.
This technique can be used to tell the difference, even if there is no oxidation. Pour a couple of drops of compound onto a white towel and rub the paint in an inconspicuous area. If the color of the car comes off onto the towel, you are likely dealing with a single-stage system. If not, you are likely dealing with a clear-coat system.
So what’s the big deal? Well, many detailing chemical manufacturers have two categories of paint-related chemicals. Those polishes and compounds designed for single-stage systems tend to be a bit more aggressive than those designed for clear coats, as evidenced by labels that include the statement, “Clear-Coat Safe.”
Some manufacturers simply create chemicals that can be used for both types of paint systems. In fact, if you’re not sure whether it’s monocoat or clear coat, treat it as clear coat.
NEWER PAINT TECHNOLOGIES
In the coming years, whether you are out in the field as a mobile detailer or working “in the trenches” in the shop, you are likely to be exposed to some paint system terminology that is not covered in the above discussion. There are some new paint technologies that have already been developed and are making their way, however slowly, into the manufacturer’s “palette” of paint system choices.
Much of the effort to switch painting technologies is being pushed by national and international regulations designed to decrease the release of volatile organic compounds (VOCs) into the atmosphere during the painting process. As all of us who have ever picked up a spray can know, paint is smelly stuff, and usually that solvent smell indicates a VOC that is certainly unhealthy for the operator to breathe, and, worse, unhealthy for our Earth’s atmosphere.
Hence the effort to reduce the usage of previously accepted chemicals, while changing the types of chemicals to be used in the future.
As mentioned earlier, the paint is “thinned” with a chemical that makes it “sprayable” — that is, able to shoot out of a spray gun. One way to reduce VOCs is to reformulate paint chemicals so that they can be thinned with water instead of solvent. So far, this type of paint is in limited use, and is only used for the base coat, upon which “normal” clear coat is applied. So, there is virtually no impact on detailers, because we will continue to treat the paint surface using techniques we have always used for clear coat.
Also known as nano-particle clear, the ceramic clear coats are being used in some Mercedes factories. The word “nano” is used to mean extremely minute, sometimes beyond what can be seen in a normal microscope. It is the extremely small, nano-sized particles of ceramic that make the ceramic clear special.
After being sprayed onto the surface, the coating is baked and hardened in the paint shop’s oven. This process results in an extensively cross-linked, very hard paint finish. The manufacturers’, of both the paint and the vehicles upon which it is sprayed, are claiming that the hardness makes nano-particle clear more resistant to scratches, mars, and etching.
Apparently, this extra hardness also makes the ceramic clear a bit more difficult to polish than traditional clear coats. There are some detail-chemical manufacturers who are coming out with product lines specifically designed for the correction and protection of nano-clears.
Unless you expect to be working many vehicles with ceramic clear coats, it is probably not necessary to buy a whole new product line. Your current clear coat chemicals will probably work fine, although you may have to spend a bit more time than you are accustomed to polishing problems out of nano-particle clears.
In this process, finely-ground particles of pigment and resin are sprayed onto the surface, which is electrically charged so that the particles are attracted to and lay on the surface in
an even layer. Then the piece is baked, which causes the particles to fuse into
a smooth coating that is uniform, durable, and known for flexibility.
In my research on this coating system, I found that this process is most often used for small parts and wheels, especially in the BMW and Volvo factories. It was unclear, however, whether or not entire vehicles are being painted with powder coat.
THE BOTTOM LINE
The bottom line for us as detailers is that, regardless of how a car is painted, we are concerned only with the protection, maintenance, care, and correction of the outer surface of the coating. For this, we can rely on trusted chemicals, equipment, and techniques that have worked well for us over the last couple of decades.
The advent of new paint technologies does not necessarily mean we have to have a separate cabinet in the shop with special chemicals and equipment — at least not now or in the near future. Treatment of the newer technologies is not so different from what we do now.
So is all this new paint technology “much ado about nothing?” Be aware of the changes, but don’t freak out about them. If you have the time and money to research new lines of chemicals designed for special vehicle coatings, by all means do so. But for the majority of us, careful use of what we already have will be fine in virtually all cases.
Prentice St. Clair is president of Detail in Progress, a San Diego-based automotive reconditioning consulting firm. To contact him, e-mail Prentice@DetailinProgress.com or call (619) 701-1100.