We first became involved with what was originally called "power painting" over 20 years ago. We were performing a Chevy "restification" and we decided to try something new. From that endeavor and experience, we came away convinced that it (now called "powdercoating") is the way-to-go in most automotive rebuilding, modifying and/or restorations-even though it is not deemed "stock" by the purists.
We are talking Chevy vehicles-mostly of the modified variety. We also thought back then that if one was dreaming of opening his own business, a powdercoating shop would be an affordable, zero-emissions, good way to earn a living. We still think the same today.
According to lore, as well as much research, powder painting/powdercoating evolved 50-plus years ago in Sweden. The first patents were said to be applied for in Germany in the early '50s. The process came to America 17 years later in the late '60s.
What is the powder?
It is a mixture of finely ground particles of resin and color pigment. It electrostatically adheres to the grounded surface, then is fused/bonded to the item due to curing in a heated oven. It flows in a complete uniform manner. It is very durable and of high quality. The entire paint process is emissions-free. Any unused powder goes to the floor where it is retrieved via broom or vacuum. Nothing goes airborne.
There are basically five different types of paint. They include polyester, polyurethane, epoxy-polyester, acrylic and polyvinylidene resin. All can be had in regular shades as well as clearcoats and metallics. There are also many gloss levels and textures available too.
How Is Powder Coating Applied?
There are two acceptable processes: First, consider small parts and large parts. All, whether steel, pot metal, aluminum, glass, ceramic, plastic or wood, must be clean. For small parts, the "powder" is put into a canister, then a vacuum hose sucks it into a specially constructed spray gun. The powder comes out of the gun and into the atmosphere in what we can describe as a "floating fog" or "mist." It adheres to the subject part via positive (+) electrolysis connected to a large, metal, rollerized rack. After being powder painted, the rack is wheeled into a huge heat room, which is usually fired by a roof-mounted gas or electric heater.
The second powdercoating method is almost always for large parts, like a vehicle frame, cab section or fencing. The clean frame, cab or fence is first heated then is dipped into a container of fluidized powder. Either can also be run through an electrically-charged "cloud" of powder paint. Just for the record, automotive buildings and shops feature many powdercoated items, including fences, railings, banisters, wrought iron, metal fixtures, as well as aluminum and stainless steel components.
The various powder paints often take a different heat temperature and length of time to fully cure. The air temperature is usually between 250-300 (F) and the overall oven curing time takes anywhere from 15-30 minutes. A timer is set for each batch of parts being cured.
Also, oven-curing temperatures over the years have been lowered so as to not damage temperature-sensitive parts, such as those made from plastic or wood. Cool-down time is usually one hour or less. Cost studies reveal that powdercoating is one-third cheaper than painting.
Masking Tape For Bearing Races, Threads, Etc.
Many types of masking tape are available depending on the job at hand. Naturally, anything with close tolerances cannot be powdercoated. Masking parts also adds labor costs to the bottom line. You may wish to do this prep work yourself.