For years, custom car enthusiasts were painting their frames, suspension components, headers, and exhausts with everyday automotive paints, only to discover after limited miles the framerails and upper and lower control arms were chipped and pitted from road shrapnel. And how about those chromed headers that turned gold and blue from the intense heat of the hot exhaust gasses? That was then, this is now.
Let's come out of the dark ages of coatings. Today's aerospace powder-applied coatings and ceramic thermal coatings can cure all of those problems.
Powdercoating:
This type of dry surface coating is applied as a free-flowing dry powder. The main difference between a liquid paint and a powdercoating is that powdercoating does not require a "solvent" to keep the binder and filler particles in a liquid suspension form. The powder is applied through a static-charged air gun or wand, which gives the powder particles a positive charge. The powder is then transformed from a powder into a melted coating by the heat of a curing oven. When it's cured, it creates a hard finish that is tougher and more durable than conventional paint.
Surface Preparation:
Removal of oil, soil, lubrication, greases, metal oxides, welding scales, and so on is essential to create a pure metallic surface. This can be done by a variety of chemical or mechanical methods. The most common surface preparation is media blasting, or abrasive blasting, which provides surface texturing, etching, finishing, and degreasing from materials made of wood, plastic, glass, aluminum oxide, silicon-carbide grit, and sand-blasting media.
Powder Application:
The powder is dispersed through a pneumatic gun that uses filtered, compressed dry air that is delivered at 20-30 psi. The compressed air is merged with the powder, which causes it to flow through the inner teflon barrel, thereby producing an electro-positive charge that attacks the powder particles, which are dispersed out of the gun barrel. The part being coated is grounded, so the positive-charged powder particles are attracted statically clinging on and around the parts surface. When the part is covered with a uniform powdercoating, the ground cable is disconnected from the part. The powder-coated part is then put into a curing oven for a certain period of time, at a certain temperature, which causes the powder to melt and flow-out.
Curing:
When the powder is exposed to elevated temperatures, it begins to melt, flow-out, and then chemically reacts to form a higher molecular polymer-like coating. This cure is called cross-linking, which requires a certain degree of temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed.