I have used them on pens that I have made to match the color of my Porsche 986 Speedster. The trick to an exact match, is to find out what color primer was used, what base coat was used (exact paint code name and number) Porsche Arena Red Metalic #xxx, and how many coats. Than how many coats of clear were used. Some cars, such as my Porsche, have a two stage paint job that requires a baking time in between coats. If your not tring to match a color exactly, make sure you use an automotive primer under your color. Primer color will change your finished color, and most pearls are translucent and need a proper base color under them. See my photos for examples of these pens. Jim S