In basic flame spraying, a hand-held device is used to spray a layer of metallic coating on the substrate. In flame spraying, the primary force behind deposition is a combustion flame, driven by oxygen and gas. Metallic powder is heated and melted, as a combustion flame accelerates the mixture and releases it as spray. This process has a high deposition rate and creates very thick layers, but the coatings tend to be porous and somewhat rough. Due to the nature of the application process, coatings can be applied to specific areas of components, which is useful when working with complex or unusually shaped components. The process is relatively easy and requires minimal training.
Arc spraying is similar to flame spraying, but the power source is different. Instead of depending on a combustion flame, arc spraying derives its energy from an electric arc. Two wires, composed of the metallic coating material and carrying DC electric current, touch together at their tips—the energy that releases when the two wires touch heats and melts the wire, while a stream of gas deposits the molten metal onto the surface of the substrate, creating a metal coat. Like flame spraying, the resulting coating typically suffers from high porosity.