Powder Coating was not an OEM process for Honda in 1965, and was industiralized much later. For the restorer, powder coating is a tool that can be used to protect parts that need to be resistant to corrosion, abrasion and survive harsh environments. For the purist, powder coating, would not be part of the restoration tool set, but for the practical restoration it is a tool that can help create parts that are even better than the OEM parts supplied with the car.
The history of powder coating begins in the late 1940s and early 1950s, at a time in which organic polymers were still being spray coated in a powder form onto metallic bases. Dr. Erwin Gemmer, a German scientist, then developed the fluidized-bed process for the processing of thermosetting powder coatings and registered an appropriate process patent in May 1953. Between 1958 and 1965, literally all powder coatings, generally only functional applications with a film thickness of 150 µm to 500 µm, were processed by means of fluidized-bed application. Electric insulation, corrosion and abrasion resistance were in the foreground. It was the Bosch company that developed the basic type of epoxy resin powder in their search for a suitable electric insulation material.
The fluid bed process deposited too high film thicknesses for practical use in numerous applications. The technology of electrostatic processing of powder coating was developed soon thereafter in the U.S.A., and commercialized between 1962 and 1964 in the U.S.A. and Europe. The technology quickly moved to a spray-guns application which allowed thinner film application.
Between 1966 and 1973 the four basic types of thermosetting resins, which are still utilized today, were developed and commercially distributed. They are epoxy, epoxy polyester hybrid, polyurethane and polyester (TGIC). The technoogy grew modestly through the 70's but at that time was considered too expensive for commercial use, color change problems and high curing temperatures greatly limited the color range, effect and substrate diversity.
Since the early 1980s, powder coatings have developed worldwide through continuous growth. This has been driven forward by continuous innovations pertaining to the available materials, improved formulating know-how, advances in application technology, plus the development of new applications (e.g. MDF and coil coating). Although restrictive environmental-protection regulations continue to rise, there will be constant growth in this market for decades to come.
Powder coating is a type of coating that is applied as a free-flowing, dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent to keep the binder and filler parts in a liquid suspension form. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a "skin". The powder may be a thermoplastic or a thermosetpolymer. It is usually used to create a hard finish that is tougher than conventional paint. Powder coating is mainly used for coating of metals that need protection against corrosive elements, such as the frame or the suspension components or even the wheels.
The advancement in powder coating materials have opened up some artistry and functionality into the finished. There are clear finishes, that can be used to tint chrome into gold or pewter. There are flat textured finishes that can be used to hide scratches and imperfections in restored parts. In the case of the wheels above, they are finished in the honda grey, with just a touch of metallic finish to set them off against the car.
Powder coating would not have been a process used by OEM manufacturers in 1965, however, powder coating finish when properly applied makes the underlying metal corrosion resistant and almost indestructible. I recomend it for all exposed components in harsh environments.
Some examples where powder coating was chosen as an option because of its durability, the spark plug covers, oil pan, air filter cover and exhaust header.
On the assembled engine, along with the bead blasted aluminum, they provide a fresh look that will not fade with time. While not an OEM finish, it is far more durable and practical. The parts installed on the engine.
Luca in Italy has done a restoration where they have extensivelly used powder coating to protect the bead blasted aluminum with a clear coat gold finish to allow the sheen of the original finish, combined with the protective properties of the powder coating. The frame is also powder coated in this example.
Courtesy of my supplier of Choice, Bonehead Performance, they have supplied a color chart that demonstrates not only the vast range of colors, but also the range of finishes and textures available.
Bonehead does most of their business through mail order so feel free to contact them.