This article was published in the October 2004 issue of Modern
Car Care magazine.
Evolution of Automotive Paint and Protectant Technology
History of Automotive Coatings
Ever since the first automobiles were made in the late 1800’s, there have been
many changes in paint technologies to protect and beautify these man made
transportation devices, from natural products to high tech polymers. In the
first part of the 20th century automotive paint technology was based on the same
air-dry varnish systems that were used for wooden furniture and horse drawn
carriages. The major drawback was that the only choice of color offered was
black. In addition, they required tedious brush application of multiple coats
and days of drying time, which created a production bottleneck.
In 1923, E.I. DuPont De Nemours developed nitrocellulose lacquer systems, which
offered many color choices and easier application using spray guns. However,
lacquer systems required spray application of 3-4 coats of paint to achieve the
desired properties. Lacquers also by their very nature have poor resistance to
certain chemical solvents. Repeated exposures to gasoline spills could stain and
damage lacquer finishes. In fact, in the 1960’s some cars had their gas tank
filler located under the license plate to avoid spilling gasoline on the lacquer
paint. Nitrocellulose lacquers were used on some passenger cars until about
1957, when solution acrylic lacquers were introduced. Acrylic lacquers offered
much improved durability and a wider range of bright, pleasing colors –
Another major development in paint technology came with “alkyd” enamel paints
that were introduced on some car and truck models in the early 30’s. Enamels
formed a very durable film through a chemical reaction after they were sprayed
on the vehicle and baked in an oven. The cured paint film was about 2 mils thick
(1 mil = 0.001”), and it was very resistant to chemicals and solvents. Enamel
paints had shorter application times also. Typically, they were applied in 2-3
steps versus 3-4 steps for lacquers. The advent of organic pigments also added
many different choices of colors to consumers. However, the alkyd enamel paint
oxidized in sunlight fairly quickly, which caused the colors to begin to show
fading and/or dulling in a matter of several weeks. The durability of enamel
finishes was improved considerably with the introduction of “acrylic” enamels in
the early 60’s.
To provide further improvements in appearance and durability, a new type of
finish, called “Basecoat/Clearcoat,” was developed and introduced in the late
70’s. The topcoat paint system was split into a pigmented enamel basecoat,
followed by a clear enamel finish. The key to this technology was the
development of a clearcoat material with superior durability in all climates.
Initially, the cost of the Basecoat/Clearcoat paint system was prohibitive and
it was only used on some high-end automobile finishes. However, refinements in
the material technology and processing helped to reduce costs, and by the late
80’s this paint system had become widespread. In fact, only a small percentage
of cars manufactured today do not use this Basecoat/Clearcoat paint system.
The benefits of this two-layer system were many. It increased the gloss of
paint considerably, which was unsurpassed by any other paint system. It also
allowed the paint formulators to incorporate UV absorbers to protect the
clearcoat and the pigments in the basecoat from oxidation. Therefore, it could
take years to show any dulling effect.
A typical basecoat paint system after the two components are mixed is shown in
Table I: General Basecoat Formula
|Petroleum –Based Solvents
Resins and Binders
Pigments & Colorants
Silicone Polymers & Other Additives (Catalysts, etc.)
A typical clearcoat paint system after the two components are mixed is shown
in Table II.
Table II: General Clearcoat Formula
|Petroleum –Based Solvents
Resins and Binders
Silicone Polymers & Other Additives (Catalysts, etc.)
In some cases, the clearcoat has two components that react and form a hard
polymeric network. The two components may be premixed or mixed right before it
is sprayed on the surfaces, depending on the polymer technology used.
While the Basecoat/Clearcoat paint system is far superior to conventional
one-coat enamel paints in many respects, it has a few disadvantages. The
clearcoat has a greater tendency to show marring when rubbed by foreign
materials; in fact even terry towels leave visible wiping marks or streaks on
the surface. Furthermore, the high reflectivity of clearcoat makes any
imperfection highly visible; therefore swirl marks from buffing are much more
pronounced. Finally, removing clearcoat by using polishing products removes UV
protectants, which can lead to loss of gloss and clarity and ultimate failure of
the paint system.
History of Paint Protectants
The history of paint protectants goes back to the days of horse drawn
carriages also. The coatings were mainly protected by applying animal fats.
Later, waxes and oils were used. The fats and oils helped seal the coatings from
moisture and kept the wood frame from drying out. They also helped increase the
gloss and the beauty of the finish. These materials had to be applied frequently
to maintain their protective properties.
This method of protecting and beautifying the finish was carried over to
automobiles, which replaced carriages. The early automobiles also had a wood
frame and had very similar coatings as well. Natural waxes and oils were mostly
used for protecting the original varnish finishes. These waxes did not contain
any chemical solvents, since they could have dissolved the paint away. The oils
offered ease of application while waxes offered longevity. Of the natural waxes,
Brazilian Carnauba (Copernica Cerifera) was one of the hardest and most durable
and offered excellent gloss.
As the car industry shifted to lacquer and enamel paint technologies, the
protectant technology improved drastically. Petroleum distillates comprised a
large portion of the new protectant materials. In some cases, abrasives were
used to remove oxidized pigments and colorants on the paint surface. This was
very visible since the polishing towel ended up being the same color as the car.
As the solvents evaporated, the abrasives dried to a powdery residue that was
wiped off, leaving some waxes and oils behind to protect the finish from the
elements. The paint was restored to its original showroom color and shine, and
waxes and oils also offered some depth of gloss.
After a few weeks in severe climates, however, the paint became somewhat dull
again and there was a need to repeat the waxing/polishing process. The acrylic
paint systems were much more forgiving and the process of polishing the finish
did not cause as much harm. Also, the swirl marks created by applying these
polishing products were not very visible even after the waxes wore off. Table
III shows the general formula for these wax/polishing products.
Table III: General Wax Formula
Petroleum –Based Solvents
Polishing Agents (Abrasives)
Natural and/or Synthetic Waxes
(Fragrance, Thickeners, Preservatives, etc.)
A significant portion of these conventional waxes/polishes is composed of
abrasive materials. Abrasives serve several purposes in these products; they act
as cheap fillers, they help spread the wax evenly and minimize streaking, and
they help remove oxidized colorants and pigments of older enamel paints.
However, the auto industry switched to the new Basecoat/Clearcoat paint
technology in the 80’s and 90’s. The traditional waxes/polishes are much more
damaging to the surface of the clearcoat. These abrasive containing products
create swirl marks that become highly visible after the waxes and oils wear off.
Also, extensive polishing can remove significant thickness of the clearcoat,
thus removing the UV protectants and causing loss of gloss and clarity. Finally,
after several applications, enough paint can be removed to cause premature
failure of the clearcoat. These are some of the reasons most car manufacturers
recommend against applying abrasive containing waxes/polishes on Clearcoat
Below are pictures of the surface of panels coated with a black basecoat and a
2- component urethane clearcoat. The panels were subjected to a typical waxing
procedure with a common commercial standard wax (Mequiar’s Mirror Glaze®
#7) and a new generation type wax (Optimum Car Wax®).
The first two pictures show the impact of the cloth used in the procedures. It
is obvious that terry towels can create heavy swirl marks on the Clearcoat
finish. Even with microfiber towels the finish can get scratched with improper
use; such as rubbing the stitching or the tag on the car finish. For this
reason, most detailing specialists remove the tag and fold the edges inward
|1. Dry Terry Towel (8x)
|2. Dry Microfibre Towel (8x)
|3. Leading brand per label directions(8x)
||4. Optimum Car Wax per label directions
The next set of pictures shows the impact of the different car
waxes. The industry standard, applied as directed on its label, leaves many
small scratches in the surface compared to the new generation wax. Once these
scratches are created on the finish, they cannot be completely removed; however,
they can be filled with wax to minimize their visible effect in the sun.
Reconditioning of clearcoat paint therefore depends on the
finish. For paint that is in good condition or the new car inventory,
non-abrasive products such as Optimum Car Wax will offer maximum protection
without damaging the paint. Abrasive containing products should only be used if
the finish is heavily soiled or scratched. In these cases, true compounds such
as Pro-Polish, Malco Tru-Grit, Auto Magic XP-Compound, or the like will do the
best job of feathering out scratches with the least amount of effort. After
removing enough clearcoat to minimize the scratches, using Optimum Car Wax will
enhance the gloss and protect the finish in the least amount of time. In all
these cases, the best results are achieved by using random orbitals or highspeed
polishers with foam bonnet.
Dr. David Ghodoussi is the President and CEO at Optimum
Polymer Technologies, Inc. Dr. Ghodoussi has over 12 years of experience as an
Organic Chemist overseeing research and development focused in polymers and
manufacturing automotive paint for Dupont and PPG. He received his Ph.D. and
Master's degrees in Polymer and Organic Chemistry from Oregon State University
and an MBA from University of Memphis. He also holds Bachelor's of Science
degrees in Chemical Engineering and in Chemistry from the University of
California in Santa Barbara.
Gene Praschan is presently consulting with the major automobile
manufacturers in the United States. Gene graduated from the University of
Michigan with a BS degree in Chemical Engineering. After working several years
on paint materials development for Dupont Automotive Finishes, he joined General
Motors Corporation at the Technical Center in Warren, Michigan. He served in
several GM divisions in managerial positions focused on development of coating
materials, and paint processing technology before retiring in 1991.