The 6 golden rules of paint preparation

Karl-Heinz Augustin
Professional tips for optimal classic car care
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S o a hopeless case is certain not in your garage, but maybe you recently bought a healthy barn find that only needs fresh oil and some cosmetics. Or, disappointed, you are pulling your US import out of the container, which does not quite deserve the optimistic rating “immaculate” (flawless). The 126 S-Class in these photos stood under a tree with a flag dealer for two years. The only thing that looked good about her were the aluminum wheels; anyone else would have rolled the car matt black to the rat. Repainting would be too expensive.

I wanted to know, drove the Mercedes painted in the rare color brown 427 to a professional reconditioner.

Premise: Only with simple means

Roberto Mercuri lives his job with passion, he runs his Quality CarCare near Heidelberg and also works on an outpatient basis with a well-equipped service vehicle . Roberto smiles knowingly as I anxiously drive up with the 280 SE: “Is there anything else?” I ask him carefully. “It's a real challenge,” he grins meaningfully. “Please no expensive miracle cures, only commercially available items that anyone can buy or have in the garage,” I say. “It's amazingly good inside, the aluminum wheels aren't corroded either, so we have to concentrate primarily on the paint,” says Mercuri. From him I learned that plain paints with a high proportion of red, including my rubellan brown, as code 427 is strangely called in some Mercedes color cards, chalk out and form a gray haze.

Of course, it is also UV-related Weathering in the game, tree sap and bird droppings do the rest. From a chemical point of view, the top wafer-thin layer of paint is oxidized. Over the years there has been an intense reaction with oxygen on the 126er, which would have prevented a protective clearcoat like the one used for two-layer metallic.

Roberto can hear the paint

' I can feel this erosion and also hear it when I run my hands over it, 'says Roberto. “The paint feels like sandpaper - and it sounds like it.” The Benz was built in 1981, at that time robust acrylic paint with a thickness of around 120 thousandths of a millimeter was applied, which can handle it with coarserAbrasives treated with abrasive in the polish to remove the dirty oxide layer.

After hand washing and drying, Roberto sprays body parts with a commercially available cleaner fluid and pulls a cleaning mineral modeling clay over the paint, which binds the dirt out of the pores . Weathered paint is as porous as lava under the microscope. The once smooth surface has become as rough as sandpaper due to unavoidable laundry rubs and external influences.

The 6 golden rules of paint preparation

To restore the shine, only sanding helps, but not with 1,000 er sandpaper as with the varnishers, but first with a polish that contains coarse abrasives. Because you can't master the approximately 14 square meters of paintwork on the 126 S-Class by hand, Roberto and I only test the effect of the agent by hand on a small area. You have to exert a lot of sweaty pressure to remove the 6 to 8 micrometer thin oxide layer with the soaked microfiber cloth.

This is of course much faster with the eccentric polishing machine. But whether by hand or by machine, Roberto Mercuri's “Six Golden Rules” always apply. First: Always apply the agent to the cloth or the polishing pad, never to the paint. Second: Work cleanly - each product gets its own cloth or polishing pad. Third: Never work in a circle, but always square in a cloister, otherwise hologram patterns will arise that can no longer be polished away.

Fourth: Work on small areas the size of a cloth. Fifth: Apply the medium sparingly - the motto 'A lot helps a lot' does not apply to paint preparation. Sixth, the polishing machine is not for beginners. Dealing with her has to be skillful, you have to let a professional show you. Too much pressure on one point heats the paint too much, with body beads the newcomer has to be careful not to sand the paint down to the primer.

Mercuri carries out three work steps in a row with the machine: The rough polishing with a wool disc , the fine polishing with the microfiber disc “medium” and the wax polishing with the gentle “velvet disc”. Even after the rough polishing, the effect is amazing. The S-Class comes out as shiny as it usually does in the rain. After hours of intensive treatment, the former matt brown, which looked so sloppy and dull as it was applied with a roller, turns into a mirror-like piano lacquer. Its deep shine inspires and could easily be used to check hairstyle and make-up for women.

Finally, Roberto drums and massages the now irresistibly chocolaty rubellan brown with rich carnauba wax and fondles euphorically with the long-pile cloth like someone who wants to make the 280 SE a concours winner. The expensive precious wax is the only luxury preparation that we can afford for processing.Every scratch and color difference on the Mercedes can now be seen under the merciless studio lamps, but from a normal viewing distance it looks like a car of the year. Waxing twice a year is enough to preserve this brilliant performance.

Before that, the reflection of the dead paint was zero. Now I can reflect myself in it. What a difference! Five lengthy, strenuous work steps have brought the plain paint back to life. But it was worth it. Only now do I know how chocolaty the DB-Braun 427 really is.

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