Flame spraying is a method of coating ferrous and cast iron metals in an inert non ferrous coat of pure metal, not paint, usually either Zinc or Aluminium.
If you look carefully in the rear of the booth you will see a open reel carrying the zinc wire, which is fed into the spray gun, melted by the propane flame, and blasted onto the surface by compressed air. This means that the spray gun has connections for compressed air, electrical feed to the wire feed motor, propane gas for the heat, and of course the wire feed itself. This is quite a handfull for the poor guy in full protective gear, and very heavy, and when I took these photographs he was on his second coating after 2 hours and was just about exhausted. All of the early GTDs were coated in this method, and all have withstood years of use with little or no coating loss or corrosion, its a very effective solution, but not many shops carry this type of operation out, and I am lucky to have one within walking distance. Powder coating or paint can then be applied for finish. Frank