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albrecht Stachel

Don't Confuse Me with Facts
Albrecht Stachel


Restoring a Classic with Modern Paint Systems

Nothing will condemn a good car to an existence in the garage as surely as an expensive new paint job. However, if you find yourself with the notion that everything is not quite enough, you might still consider refinishing your car. I can’t deny that my heart beats faster as I look at a straight, well-painted automobile and, financial vulgarities aside, the rush of anticipated adoration and envy is some of what restoration is all about. An automobile’s presence is grounded in the fit and finish of the body with all of its wonderful chrome. In turn, quality paintwork is a reflection of the work done to bring the fit and finish of the body to a high degree of straightness prior to painting.

Painting a car is about labor. The time spent eliminating rust, straightening damaged sheet metal, and sanding every surface mirror-smooth makes good paintwork expensive. But that’s not all there is to it. Should you desire to go so far as to restore a car’s body and coatings, it is essential to remove all trim and attached body panels. Disassembly can be an onerous task, but it must be done in order to properly prepare, protect, and coat the sheet metal from all angles. Add to this the labor of careful reassembly following refinishing, and you have a considerable investment in time alone.

This labor equation will be true whether you do this work yourself or pay someone to do it. However, if you do it yourself, it will likely take longer. This is not only because you may be learning as you go, but mainly because restoring your own car presents infinite opportunities for improvement. It can be difficult to muster the willpower necessary to declare your efforts “good enough.” One of my coworkers likes to say, “The worst enemy of good is better.”

With abundant modesty, I do not consider myself an expert in the automotive refinishing world. There are many people in this field who live paint, and it’s such a huge subject, I cannot cover it well here. Painting Mercedes cars has been for me a part of the greater task of restoring Mercedes cars. While a stint at the BASF paint school and many years in the school of hard knocks have taught me how to accomplish this work for our customers with some alacrity, the shared thoughts here merely represent my own experiences and observations.

On that note, I am embarking on painting a 1959 300d (W189), I have owned for decades. After years of consideration, imagining every possible color combination for body and interior, I have settled on a dark blue body with a gray leather interior. The interior is out of the car and the trim is off. The doors are gutted and the entire driveline has been removed. Lifting the body from the frame seems unnecessary in this case, since the car will be a driver, but I do want the panels to be extra straight. Because I am in the business, my car will invite critical examination, and meticulous bodywork and block sanding at each stage will be a necessity. On a car the size and complexity of the 300d, this will require Zen-like devotion to the craft.

I have also given thought to the gloss hold-out of the paint finish. Because this car will not be shown, I have succumbed to the lure of a contemporary high-gloss, low-maintenance clear coat, in contrast to the deep, lustrous, hand-polished show finish we might supply for a restoration. The difference in appearance between the two is like comparing a glass table top to the finish on a grand piano.

It is worth noting, as we touch on the issue of originality of paint, that even Mercedes-Benz now employs modern water-based paint for the in-house restoration of its important vehicles. In a recent press release describing the restoration of the second W194 300 Gullwing racer ever produced, the restorers state that, “Replicating the car’s paint presented an interesting problem as the original nitro-lacquer ‘silver bronze’ paint is no longer available and its use no longer legal. So the original paint supplier matched the matte finish paint as closely as possible in a modern, water-based formula.”
It is common knowledge that today’s automotive paint is different from what was used in years past. From the prewar era to the immediate postwar period, Mercedes-Benz employed what is termed “nitrolack,” or nitrocellulose lacquer, a chemically simple paint that was introduced in the 1920s as the first automotive paint available in a variety of colors other than black. While versatile for its time, nitrocellulose paint has become infamous for tending to crack rather than flex. In the 1950s and 1960s, a decreasing number of Mercedes cars were painted with nitrocellulose paint, and an increasing number with acrylic lacquer, a more flexible and forgiving synthetic material that came into full use in the refinishing industry in the 1960s.

Acrylic enamels were followed by polyurethanes in the 1970s and 1980s. Polyester formulas became the norm for undercoatings and fillers, and isocyanide agents were introduced to accelerate the drying process. Forced drying in a combination spray booth and low-temperature oven became standard.

More recently, water-borne chemistry has begun to displace solvent-based systems as environmental and safety standards have become more stringent. Now refinishers are obliged to use only coatings that are in compliance with current local regulations, and water-based paints are most commonly used.

Modern automotive coatings have moved well past the layers of paint that characterized the nitrocellulose coatings of the early 1950s. Current factory paintwork involves full-body-bath rustproofing, and filler with top coats applied with rotating electrostatic atomizers. Since the mid-1980s, factory coating has moved toward automation, and is today largely performed by robots.

Before refinishing your vintage car, you must determine the appropriate extent of your involvement. Will you be embarking on a partial refinish where only some of the car will be repainted, as in the case of accident damage repair? Or are you considering a renewal, that is, another coat of paint over the old coat, or will you be undertaking a complete recoating of all surfaces?

If you are committed to a partial refinish or a renewal, it is essential that you ascertain what type of paint the vehicle is currently finished with. Rubbing the surface briefly (in an inconspicuous area, please!), with a cloth soaked in lacquer thinner makes things obvious: the color of nitrocellulose or thermoplastic acrylate paints comes off readily in the process and paint left behind becomes somewhat tacky, while more contemporary paints will resist the application of lacquer thinner.

If you are doing only a partial refinish, and your car is finished in a paint type that is still available, you may enjoy some success in matching and blending in modern paint. However, if a vehicle has already had total re-sprays or refinishes, it is advisable in any case to remove all of the paint layers by sanding or stripping. Chemical and physical tension between different paint chemistries or systems may cause any new paint application to fail in short order. Mainstream refinishers commonly employ “sealers” to avoid stripping off old finishes. But even if a passable chemical bond can be achieved by this means, corrosion under the old paint is likely to go unnoticed until it is too late. Nothing pains the pocketbook quite like rust bubbles or lifting paint appearing under a new five-figure paint job.

Each of the paint chemistry developments has increased the cost of refinishing materials. A recent in-house order brought to my attention that nearly all colors of standard high-quality paint now cost more than $100 per pint. Volume discounts still apply, but I believe refinishing to any decent standard, let alone show quality, may be approaching unbearable levels of expense for all but the most devoted owner. The upgrades in equipment necessary to remain current with regulations and technological advances will likely price some small operators out of the game. I expect to see a decreasing number of shops with knowledge of older processes, with personnel willing to devote themselves to show-level tasks such as hand-sanding.

In short, if quality paintwork is in your car’s future, there may never be a better time to embark on this process. Costs will only increase, and expertise generally decline, as time goes on. Skills needed for show-winning paint and bodywork will repose in fewer and fewer organizations.

When you decide to paint, do not abdicate responsibility once you have commissioned the work. As with any restoration work, it is vital to let the folks to whom you have entrusted the job know precisely what your expectations are. Be sure to let them know if you expect the car to maintain its new looks for five years, or 50. The greater the longevity goal, the more preparation time is involved, and the more the job is likely to cost. Great paint jobs, like any great work, are the result of attention to detail and proper preparation, as per the “7 Ps” often cited in the military.


Evolution of Paint Finishes

Nitrocellulose Lacquers
Introduced by DuPont in 1923 or 1924 and used through the mid-1950s, the now-infamous nitrocellulose lacquers were the first automotive paints in colors other than black.

Acrylic Lacquer
Acrylic lacquer was developed as a replacement for the nitrocellulose lacquers. It is both more labor-intensive to apply than acrylic enamels and more forgiving, as many repeated spray coats are needed and mistakes such as runs or drips can be easily corrected in the sanding of each successive coat.

Alkyd (synthetic) Enamel
Still in limited use today, alkyd enamel was developed in the 1930s. Like lacquer paint, it cures through solvent evaporation but develops a gloss without polishing though absorption of atmospheric oxygen.

Acrylic Enamel
Acrylic enamel is a harder, more durable version of synthetic enamel first used in the late 1960s. Like synthetic enamel, it dries through solvent evaporation and cures through absorption of atmospheric oxygen, and it was the first paint to incorporate a modern metallic look and while it is solvent-based, it becomes insoluble after curing.

Polyurethane Enamel
Developed for the aviation industry in the mid-1970s and adopted almost universally by the auto industry in the 1980s, polyurethane enamel generally replaced acrylic enamels and is still widely used. It is a high-durability base and clear coat, with excellent color properties and depth.

Acrylic Urethane Enamel
Sometimes called polyester, this is modern car paint, found on almost all new vehicles. Developed as a durable, chemically resistant paint in compliance with emissions laws, water-based acrylic urethane enamels are the most durable coatings available at this time. They are also among the most expensive and poisonous paints on the market.

Clear Coat
Chemically, the clear coat is a sprayable plastic acrylic urethane that was developed to allow the basecoat to do the work of carrying the pigment. It gained widespread acceptance with the emergence of metallic colors in the 1980s. Applied in layers, it bonds with the color, contributing strength and flexibility, and cures into a hard, glossy shine.

Waterborne Paints
Because in many cases they’ve been developed more recently than comparable solvent-borne coatings, water-borne paints in some applications offer better hiding and blending in addition to their environmental and safety benefits.