how to apply touch up paint on bare metal
Spend enough time working with cars and eventually you're going to spend some time dealing with rust. Although newer cars are getting better and better with preventing rust, the fact is that it's a natural process that cannot be stopped - only slowed.
Rust occurs when the metal from your car is exposed to the common acids in water. This can be the result of a major accident, but more often occurs from the everyday dings and scratches to your car's outer coat of paint.
When repairing or restoring a car with rust damage or exposed metal, it is critical to properly treat the area in order to stop the rust in its tracks and prevent new rust from forming. As with any touch-up job, the first step is to cleanse your car of all water- and solvent-based contaminants. This can be accomplished by simply following the steps in our article on Preparing an Area for Touch-Up Paint.
Once the car has been effectively rid of contaminants and surface dirt, it's time for sanding. I recommend a 600 grit sandpaper. This will remove the rust, while also giving the surface a clean, smooth texture.
Next step is to apply a Self Etching Primer. For best results, you'll need to apply 2 - 3 medium wet coats, with at least 10 minutes of drying time between each coat. Not only will this primer help to prevent rust from forming, but it will also give your new basecoat something to bite into.
Allow at least 45 minutes for the Etching Primer to dry, then lightly sand with a 1000 grit sandpaper. As with the initial sanding and primer application, this light sanding will continue to create a smooth surface, ensuring a greater adhesion of the basecoat.
After sanding the primer, you will want to remove any excess primer dust by simply rinsing the area with water. Once the surface is dry, you're car is ready to withstand the brutal onslaught of rust and you're ready to apply your basecoat.
Be sure to reference our article on Applying Touch-Up Paint to make sure the application of your basecoat goes as smoothly as the preparation.