Painting over chrome isn’t as easy as regular metal. The common misconception is that chrome is used as a protectant because it doesn’t corrode. The reality is exactly the opposite — chrome almost immediately oxidizes or “rusts” when it comes into contact with oxygen. But chrome oxide “rust” is completely clear and very fine, providing a glass-like shine over the nickle plating beneath, and a finish that’s smooth and slick to the touch. Painting directly onto chrome, you’re effectively spraying a shell over very fine “rust” — this reality necessitates somewhat more intensive preparation to keep your new shell of color from simply falling off.
Wash the chrome piece with basic soap and water and dry it thoroughly.
Sand the entire piece with 220- to 320-grit paper and use 120- or even 60-grit for specific areas if you have deeper scars, rust or pits. You must get below any damaged spots. A pit in the chrome left alone will pop out in no time and ruin your paint. You may even need to use a grinder if the 60-grit paper will not get you below the damage. Follow up on the entire piece with 320-grit paper; your objective is to have minimal scratching from the previous sandpaper and end with a 320-grit finish. Always wear safety glasses if you use a grinder.
Fill in any low spots in the metal from deep sanding or grinding either with liquid steel from a tube or glazing compound if the fill-in area is less than 1/8-inch deep. Once compounds are dry, sand level to the original surface with a heavier grit and follow up with 320 grit.
Using a clean cloth or tack rag, wipe the piece off to completely remove all sanding dust, and then wipe down the piece with either lacquer thinner or wax remover.
Put on your face mask and spray the entire piece with the self-etching primer. Two light to medium coats will do. Allow time to dry between coats. This special primer will grip to the metal and prepare you for regular primer and paint.
Once the self-etching primer is dry, spray two to three coats of the high-build primer over it, always allowing each coat to dry before applying another one.
Inspect the piece visually and also by rubbing your hand over it, and use glazing spot putty to fill in any remaining flaws or pinholes in the primer. You can get a better feel for flaws if you wear a cloth glove and run your hand over the piece slowly.
Sand any glaze down with 220- or 320-grit paper and then sand down the entire piece, including the edges, with 600-grit paper so that you end up with a very smooth finish. Be sure to sand down any runs you may have from the primer. Chips or flaws will show up even more once paint is applied, so spend time here to obtain a smooth surface.
Wipe down the piece again either with lacquer thinner or a wax-and-grease remover. Any oils, dust or debris on the piece right before painting will affect your paint job in a negative way. You don’t want to remove the primer, so just a once-over should suffice.
Spray two to three light to medium coats of the paint, being very careful not to let the paint run. The nozzle head should be about 8 to 10 inches from the target, and it is better to spray in even spurts rather than holding the nozzle down the whole time, which would more likely give you runs and heavy spots. If you develop any runs, you will have to wait until the paint is completely dry–probably by the next day–and sand the runs down with fine grits of 1,000 to 1,500, then respray the piece.
Spray two to three coats of the clear-coat finish over your paint once it has dried at least 15 to 30 minutes. Be sure you have good lighting for this, since the clear will not show a color to follow but only a shine on the sprayed areas. Sometimes you have to observe your work from an angle.
Let the clear coat dry for two to three days, and then you can use a very fine rubbing compound to give you a very smooth, flat finish, which will remove any small flaws, runs and bumps from the clear coat. The compound will also provide a brilliant shine. Apply the compound with a wax applicator, let set a minute or two, and then buff out by hand — or you may decide to use a power buffer with a wool pad if it is a larger piece. You may now also apply your favorite wax after the compound to further enhance the shine and offer more protection to your finish.