Caring for single-stage paint on a classic without ruining it

Somewhere around the late 1980s, most manufacturers moved to a base coat plus clear coat system. Before that, the color and the gloss were the same layer. That layer is what we mean by single-stage paint, and about a third of the cars that come through our doors still wear it.

If you own one, the most important thing to understand is that there is no protective clear coat above the color. Every pass with a polisher removes pigment. Get it wrong and you do not dull the finish, you thin the color itself.

How to tell what you have

The simple test is a clean applicator with a mild polish on a hidden section, usually a door jamb or under the trunk lid. Wipe, then look at the pad. If the pad comes away tinted with your car's color, you have single-stage paint. On a clear-coated car the pad stays grey or white.

On a 1968 car with original paint, the pad will come back distinctly red, blue or whatever the car is. It is startling the first time you see it.

Washing a single-stage car

Everything gets gentler. Single-stage paint, especially after fifty years of sun, is porous and chalky on the surface. Aggressive soaps strip what little oil is left in it and accelerate the oxidation.

We use a pH-neutral soap, cool water, and we never let the car dry in the sun. We also avoid pressure washing anywhere near seams, badges or chrome trim on these cars, because old seals and old body filler do not appreciate it.

• pH-neutral soap only, never a degreaser and never dish soap
• Wash in shade or indoors, always
• Blot dry immediately, do not let water sit in seams
• Keep pressure washers away from trim, seals and emblems

Polishing, carefully

Oxidation on single-stage paint responds beautifully to polishing, often more dramatically than on a modern car. A chalky, faded red can come back to a deep gloss in one session. That is exactly what makes it dangerous, because the result is so encouraging that it is easy to keep going.

We work these cars with a soft pad, a finishing polish and a great deal of restraint. We stop as soon as the gloss is even, rather than chasing every last defect. Deep scratches on a fifty-year-old car are part of its history, and taking them out often costs more paint than the improvement is worth.

We also do a test area first and invite the owner to look at it before we continue. Several times a year, someone looks at the test section, decides that is exactly enough, and we stop there.

Protecting it afterwards

Traditional carnauba wax remains the right choice for most single-stage cars. It feeds a little oil back into the surface, it looks correct on period paint, and it can be removed easily if the car is ever restored or resprayed.

We will apply a modern sealant or coating on a classic if the owner asks, particularly on a car that gets driven regularly. But on a concours car or an original survivor, wax twice a year and a careful hand wash will keep it looking right for another two decades.

The principle we work to on old cars is simple: do the least that achieves the result, and never do anything that cannot be undone.