Spray application of coating compositions utilizing induction and corona charging means

A method of applying a sprayable liquid coating composition to a workpiece, said composition having an electrical conductivity between about 0.005 and about 0.06 .mu.mho/cm, said method comprising spraying said composition by employing a spray gun having:

• (a) a gas nozzle and a fluid nozzle, each of said nozzles being in cooperative spatial relationship with each other to cause a fluid stream of said composition issuing from said fluid nozzle to be atomized and sprayed as fluid particles by gas issuing from said gas nozzle,
• (b) electrically grounded means for increasing surface area from which fluid particles can be formed, said means being disposed within said fluid stream and having at least one sharp edge, and
• (c) induction charging electrode means disposed adjacent said gas and fluid nozzles and having a rear edge located rearward of a plane which is perpendicular to the axis of liquid flow and which passes through the discharge point of said fluid nozzle;
• said method further comprising supplying sufficient voltage to said induction charging electrode means to produce a corona discharge at said sharp edge of said surface area increasing means, said method producing corona charging and induction charging of sprayed fluid particles.