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There’s more to paint

india Updated: Aug 28, 2009 11:26 IST
Grease Monkey
Grease Monkey
Hindustan Times
Highlight Story

We’re (finally) done with suspension, so you can now heave sighs of relief. Not audible ones, you in the back.

We’ll now go from what’s under the car to what’s on top of it — the paint.

Why paint a car at all?
After all, no paint means no worrying about scratches or dents, or body repairs that entail heating and beating, or shade-matching and baking. Today’s automotive paints’ primary draw to the customer are in their visual appeal, but their beauty isn’t merely skin deep.

Car bodies are made up of metal and plastic parts. The hood, roof and doors are usually metals like mild steel or galvanised iron, and the bumpers (or fenders, as the Americans like to call them) are made of plastic. The plastic bits are prone to fade and crack faster, and the metal bits have one major enemy in rust. Back in the day, manufacturers would spray an anti-oxidation layer onto the metal body shell by hand, with a spray gun.

This paint was similar to what is commonly known as ‘red oxide’ — the same stuff you coat the grilles on your windows with, before you slap on the actual coloured coats.

Dunked in a vat
These days, the primary coat is applied by dipping the entire body in a vat of paint. This is done right after all the different parts of the body are welded together. Some factories have a conveyor belt that goes downward into the primer, and they emerge baptised with the primer.

Honda Siel Cars India has a more fun way of doing it — the conveyor belt itself does not dip, but the body rotates vertically, like a gymnast on the parallel bars. This somersault makes the body dip into the vat of paint when it is upside down, and it comes up with a fresh coat of paint.

If you’ve ever wondered why a touch-up job never seems to be as good as the factory one, well, it is because it isn’t. At the factory, the first coat is ‘electro-deposited’. This is quite similar to gold or silver plating, where the object to be plated is effectively an electrode in a conducting solution. In the case of the paint, the body is an electrode, and the vat of paint is the other electrode. This helps the paint stick better to the body.

The body is also baked in an oven (just like bread) to help the paint affix itself to the body. An air-dried paint finish will never be as good as a baked one, which is something people don’t usually know. This is why air-dried touch-up jobs fade, bubble or crack before the original paint does, even though they’re newer. A few coats of paint are applied, since one coat isn’t enough, either for protection or to give an even finish.

The colour is topped off by a ‘clear coat’, which is a transparent coat. The transparent paint gives the car a deeper, glossier shine, and protects it as well.

A whole palette of choice
One of Henry Ford’s famous quotes was “You can have any colour you want, so long as it’s black.” Today we’ve got a million colours to choose from, but there are just three basic types of paint available to the average Joe.
First, solid colours. These are the paints that look like poster colours applied to a car, they look the same shade from any direction. Done right, they look deep and rich and are easy to touch up.

The second kind is metallic paint, which has tiny metallic flakes in it that make the paint look like there’s a million little stars mixed into it. These flakes are especially noticeable on a clean car or motorcycle in sunlight. The third kind of paint is pearlescent paint, what you’ve probably heard of by it’s shortened form: ‘pearl’, as in ‘pearl white’.

We’ll discuss pearlescent paints and how to take care of your automobile’s paint next week.

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