If you take your car to a paint shop, they’ll ask to repaint the entire panel. Depending on the severity of the case, they can do color and clear, or start all the way from the primer up.
So how does it work?
They’ll start by washing the panel thoroughly.
If the problem is on the hood or trunk, or somewhere else easily removable, they’ll remove it for easier access. Otherwise, they will have to mask the adjacent panels, sometimes the entire car, to prevent overspray.
Next, the painters will sand the entire panel free of clear coat and level the base coat to remove any oxidation and other damage. Typically, 400 to 600-grit sandpaper is used for this stage. If the paint is too far gone, they’ll sand into the primer layer and use as rough as 220-grit, then sand their way up to get a finer surface.
The panel will be washed with water, then cleaned with a degreaser, and finally wiped down with an isopropyl alcohol and water solution to prepare the surface for painting.
If they sanded the panel all the way down, they’ll start by applying a primer on the affected areas. Once cured, they’ll sand with 1500-grit sandpaper to level the panel and get a good base surface.
Next, the color is matched to the vehicle. If it’s a factory color, these go with a code, so it’s easy to replicate in any paint shop. If it's a custom color, it takes a bit of trial and error until they get it just right.
Several coats of color are sprayed onto the panel. The bare minimum is two, but they’ll likely go with more if they had to strip it down all the way to the primer.
Of course, applying the paint is its own art and science. The proper compressor settings, paint gun nozzle, distance from the surface, overlap, and flash times between coats are all instrumental for getting a great consistent finish. So is the steady hand of the painter themself.
Finally, the clear coat is sprayed. A polyurethane clear coat is mixed with the right amounts of reducer and hardener to make it thin enough to spray well, but dry out solid quickly after application.
Usually, three coats are applied, with the final one being a little heavier to ensure the entire surface is covered and sealed. Each individual coal is left to flash for 5-10 minutes before the next one is applied.
After 24-48 hours, the clear coat will have cured enough to return the car to the customer. Full curing occurs after 7 days, but you shouldn’t use any wax, ceramic coating, or paint protection film for at least a few weeks to 1 month to allow for any off-gassing to occur.
Sound like a huge hassle? That’s because it is, and it’s not going to come cheap. Expect to pay at least a few hundred dollars to repaint a body panel, and a few grand to repaint an entire vehicle.