This paint may be purchased only at True Value Hardware stores.  The product  is called PDS-6 Flat Black.  It is an Interior/exterior paint.  It is the only product we recommend for touch up.  The color matches our patina very well.  Other paints will not match as well, don't use them.

 Spray in short bursts of one or two Seconds from a distance of 12 inches.  Slowly bring the can closer until the problem area is covered.  This will also help to blend the transition from the painted area of the piece to the patina area.  Try not spray a "heavy coat" or the paint will not blend as well with the patina.