How to Touch up Spots on a Car
Touching up rust spots, dings, and paint chips on a car is one of the easiest and cheapest car repair jobs. Repairing these spots adds to the value of your car. Repairing them before they get worse saves you having to spend much more money later on costly body work.
Start by cleaning the area you will be working on, using soap and water. Rinse and let dry.
Lightly sand the spot until all rust is gone and the area is smooth. A fiberglass rust brush is perfect for this, but you can also use fine emery or aluminum oxide cloth or sandpaper. Don't use a medium or coarser sandpaper, which will show up later under the finished paint job as sandpaper scoring. This looks ugly and also makes it easier for paint to chip again.
If the rust or scratch goes deep, fill the area with body filler until it is level. Do the same for dings after stripping away the surface paint. Let the filler dry, then sand again until the area is smooth.
After you finish sanding, clean the area well with a soft dry cloth. It is important to remove all the metal, paint, and filler dust before you begin painting.
Apply primer to the spot. This is what seals the area against future rust. Primer also keeps your exterior paint from sinking into the filler and causing paint sinkage and edging, which looks ugly and makes it easier for paint to chip again. Let the primer dry.
Apply paint to the spot. The paint should be matched as closely to the car's color as possible. Some paints are not compatible with others. Cheaper paints can be lifted right off by better quality paints. If in doubt, you can test this in an inconspicuous spot. Use several light coats rather than one heavy coat, letting the paint dry between each coat. Overnight should be enough time for each coat to dry.
For best results, finish by applying clear coat to the spot. Let the clear coat dry, then wax and buff. Some paints may require a final polishing with rubbing compound.
When applying primer and paint, use a brush only when the spot is smaller than a dime. Paint pens are okay for minor key scratches, but never use paint pens on spots larger than a pencil eraser. Larger spots should always be sprayed.
Bodywork should never be done in direct sunlight. Paint also won't dry well in wet or humid conditions. If in doubt, test the clear coat first. If it dries with white streaks, it is too damp to paint well. Ideal painting weather is around 70 degrees F and with humidity at 50% or less.
If you are working in an enclosed space, wear a mask and make sure there is adequate ventilation. It is a good idea to leave the garage door open while working.
