By Jim Kerr
Many coloured parts of our automobiles leave the factory with a finish that is not paint. Everything from oil filters to alloy wheels are often covered with a powder and baked. The process is called Powder Coating and it is a tough, durable finish that should be considered if you have metal car parts or even lawn furniture that needs refinishing.
Powder coating is used for many items. That playground equipment that looks so shiny and colourful is probably powder coated. The air seeder or combine you see in farmer’s fields will likely have powder coated parts. Even the washer and dryer in your house may have been powder coated.
Preparation is the key to powder coating a part, just like preparation is the key to a good paint job. Powder coat finishes can be applied to a wide range of materials but they must be able to withstand baking in an oven at 200 to 400 F for several minutes. This rules out most plastics but steel, iron and aluminum are ideal candidates for powder coating.
Before the part is coated, it must be cleaned of oil, dirt and rust. This can be done chemically, but many small custom powder coating shops will wash the part and then “blast” it with an abrasive grit. Sand blasting used to be common but many shops are going to better blasting materials that work faster. For delicate parts where detail is important, you might want to have the parts glass bead blasted before taking it to the powder coating shop, as glass beads will clean the part without eroding much of the detail finish.
With the part blasted, some shops use a chemical etch to provide extra bond to the metal. Other shops move right on to applying the powder. I haven’t seen a big difference in the quality of work with either method, but if the parts are going to see a lot of service in a harsh environment, the chemical etch might provide a slight advantage.