Vintage and Auto Restoration - Paint - Restoring Radiance - FZ Restoration Livermore

 

With so many different paint types available today, choosing the right kind of paint to refinish your old car or truck can be one of the most difficult decisions facing car owners. Do you choose the type of paint that is correct for your era-built car, or do you upgrade and go with a more durable urethane for a longer lasting finish? Choosing the correct paint type will not only affect the cost of the refinishing process, but it can have a long-term effect on your car's value.

The varnishes that originally coated the earliest collector cars were direct descendants of furniture finishes used on horse-drawn wagons. While they could be applied with spray-gun technology developed in the 1800s, they required extensive hand finishing to develop lasting polish and regular maintenance to hold up for more than a year or two. A more modern lacquer finish was introduced in the 1920s that offered vastly improved drying times and, with much hand rubbing, a beautiful finish. These were single-stage systems, in that the paint was also the outer coating and carried both pigment and elements needed for a shine.

Change in this arena has generally been glacial, with new technologies emerging over the course of decades. Today, almost all new vehicles are refinished with a non-glossing urethane basecoat followed by a catalyzed urethane clearcoat-these are the common multi-stage "2K" systems. Over the last 20 years or so, these complete "finish systems" from a number of manufacturers have become the generally accepted way to refinish a car.

For those owners seeking a factory-correct restoration, these modern multi-stage urethanes are incorrect for nearly all collector cars. Compared to the old lacquers and enamels, urethanes are much too shiny-almost plastic in appearance due to the clearcoat-and don't have the same depth of finish that a lacquer finish has. They are also very dangerous for the average home hobbyist to use because they contain isocyanides; unless a paint mask with a fresh-air feed is used, the isocyanides-contained overspray will harden in your lungs and kill you. However, if you aren't interested in showing your old Mercury or Packard on the national level, and plan on having a professional paint your car instead, then modern urethanes are the way to go as they are far more durable than lacquer and acrylic enamel, hold up better to the acid rain and the sun's ultraviolet rays, and require less maintenance. But remember, a show judge will know the difference between this modern coating and something correct for the era.

Fortunately for the enthusiast, single-stage acrylic enamel and lacquers are still widely available. They require a little more manual labor than high-tech finishes (especially lacquer which needs to be color-sanded and buffed to achieve a shine), but that labor can produce a truly beautiful and authentic finish that can be achieved right in your very own garage. Acrylic enamel is often combined with a catalyst (also called hardener or activator), which makes the paint quite toxic. Without the hardener added, acrylic enamel will take longer to cure and the final finish will not be quite as hard, but you can still achieve excellent results.

If you are going for a truly authentic finish on a 1950s or older car, nitrocellulose lacquer is the required paint; yes, it's still available from a few specialty shops. You can make a lacquered body look terrific, but you'll spend an awful lot of time sanding and polishing to obtain an illustrious finish. Synthetic enamel used on Depression-era cars (and by Earl Scheib) is also still available.

Whether you decide to paint your car yourself or have it done professionally, it's not going to be cheap. Paints have increased tremendously in recent months due to rising petroleum costs and stiffer environmental regulations, which are forcing the manufacturers to constantly revise their paint formulas to meet the EPA's ever-changing regulations. And if you want your new paint finish to be as flawless as it can be, the use of a spray booth is almost mandatory. Of course you can build a make-shift booth using plastic sheeting if you have the space, but the better option is to rent time at a professional facility with good things like air filters, ventilation and lighting. Lastly, you'll need to practice your technique before you actually apply that $300-a-gallon paint on your car.

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! They gained great favor due to the ability to apply them quickly with a spray gun, and a good, if brittle, finish was created through repeated coating, hand rubbing, polishing and waxing. Sought after as an original finish, nitrocellulose lacquer is still available in limited quantities from specialty suppliers (see sidebar) and is today used on musical instruments and fine furniture.

Acrylic Lacquer
Acrylic lacquer was developed as a replacement for the nitrocellulose lacquers. Used extensively by GM, it is still available for certain applications. 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; it's a good choice for the inexperienced hobbyist. It can be sanded and polished to a blue ribbon finish and air-dries extremely quickly. It doesn't require anything other than a thinner for spraying; a clear coat can be added for extra protection. This generation of lacquers is still popular for show-quality refinishing; it is possible that they will soon be phased out due to environmental regulations.

Alkyd (synthetic) Enamel
Still in limited use today, alkyd enamels were developed in the 1930s. Like lacquer paint, it cures through solvent evaporation, but develops a gloss without polishing though absorption of atmospheric oxygen. Curing times can be shortened through baking, making it popular for mass production, otherwise it can be somewhat slow to dry, making it difficult for the home hobbyist without a spray booth to achieve a dust-free finish. Synthetic enamels are neither easy nor safe for home use, will dissolve in the presence of solvents and thinners, and are perhaps the least popular finish.

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. While it is solvent-based, it becomes insoluble after curing. It is a relatively fast-drying enamel, dries to a high gloss with relatively high strength and good coverage. It is one of the most affordable paints to buy today and can be top-coated with clear for added protection.

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 also still widely used. It is a high-durability base and clear coat, with excellent color properties and depth. Once it is prepared for application with a hardener and catalyst, it starts curing and can't be stopped, although its dry time can be sped up or slowed down through the use of specific reducers. As they were developed for a production environment with heat curing, they are difficult to use safely and effectively without professional facilities and safety gear.

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. The many formulations available offer a wide range of bright colors with good depth and clarity and a high-gloss finish. Reducers are used to reduce the viscosity prior to spraying, and hardeners/activators/catalysts are added to start the chemical bonding process within the paint. Assorted acrylic urethane enamels are the most common way to replicate factory finishes of the last forty years. They are also among the most expensive and poisonous paints on the market.

Clearcoat
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 from Japan in the 1980s. Applied in layers, it bonds with the color, contributing strength and flexibility, and cures into a hard, glossy shine. Clearcoat prices are usually in the same range as the base coat mixture, and are all catalyzed urethane, which contains isocyanides. For more information on isocyanides, look up the word "cyanide."

Water-borne 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. All urethane paints are water-borne, but they still require that the painter take extensive safety precautions in a positive-atmosphere spray booth including a sealed respirator and full-body protective clothing.

source: http://www.hemmings.com/hmn/stories/2005/07/01/hmn_feature7.html
by David Traver Adlphus

http://www.fzrestoration.com