In the flame spraying process, molybdenum is fed in the form of spray wire to the spray gun where it is melted by a flammable gas. Droplets of molybdenum are sprayed onto the surface that is to be coated where they solidify to form a hard layer. When larger areas are involved, thicker layers are required or special requirements regarding adherence have to be met, the arc spraying process is often preferred. In this process, two wires consisting of electrically conductive materials are fed toward one another. These are melted due to the firing of an arc and projected onto the workpiece by compressed air. A more recent variant of flame spraying technology takes the form of High Velocity Oxygen Fuel Spraying (HVOF). Due to the particularly homogeneous melting of the material particles and the very high speed at which they collide with the workpiece, HVOF coatings are very uniform and are characterized by a low surface roughness.