Paint correction in Punchbowl

Think of a scratch as a trench in the top layer of paint. You either fill the trench, or you lower the ground on either side until there is no trench. That is the whole of it, and which one you are being sold is the question to ask.

Glazes and filler polishes take the first route. The car looks corrected when it leaves and it looks like it did before after a few washes, because the filler has gone and the grooves were always there. Very cheap correction is nearly always this.

Correction does the second thing. A machine polisher with an abrasive compound removes a microscopic amount of clear coat until the surface is level again. The scratch is not hidden, it is gone, because the paint around it has come down to meet it.

That is why corrected paint looks like a different colour rather than just shinier. A flat surface reflects light as a clean image; a swirled one scatters it. Black paint goes from grey to black, and it is the single most dramatic change we can make to a car.

Clear coat is finite and does not grow back. A factory panel carries a limited thickness of it, and every correction in that panel’s life uses some.

We take depth readings across the car first. Thin readings change the plan: a panel corrected twice already, or resprayed badly, may only tolerate a light single stage where the rest of the car could take two.

Readings also reveal previous repairs. A panel reading dramatically thicker than its neighbours has almost certainly been resprayed, which is useful information if you are buying the car and were not told.

Then test sections, to find the least aggressive combination of pad and compound that achieves the result rather than reaching for the hardest cut available.

This is the reason most correction gets booked. A coating is transparent and cures over whatever is underneath, so applying one to swirled paint seals those swirls in for the life of the coating, which on a good product is years.

After correction every panel is wiped down to strip polishing oils, so the coating bonds to bare corrected paint rather than to residue. Skipping that is why some coatings fail within months while the same product on the next car lasts years.

It also works the other way around: a coating is what stops you needing correction again, because it makes washing safer and easier.

The condition of the paint drives the price more than anything else, and two identical cars in the same colour can differ by a thousand dollars purely because one has been through automatic washes for five years.

Then the number of stages, then size, then colour. Dark paint needs more work to reach the same visual standard and is the colour people most want corrected.

That is why an accurate quote needs photos taken outside in daylight, or the car in front of us. A description of the damage is almost never enough.

Etching is a defect in the clear coat rather than on it. A bird dropping left in the sun, or hard water dried on a hot bonnet, eats a shallow crater into the surface. A wash removes the deposit and leaves the crater.

Shallow etching corrects the same way swirls do: the surface around it is levelled until the crater is gone. Deep etching that has gone a long way into the clear coat sometimes reduces rather than disappears, and we will say which after a test section.

Once corrected, a coating gives you the time to get the next dropping off before it bites, which on a car parked under a tree in Punchbowl is the whole game.