A torch introduces oxidizer into a passage so as to swirl the oxidizer about a central axis, while fuel is introduced at a location spaced apart from the central axis, where the swirling action of the oxidizer is strong, resulting in rapid mixing of the fuel and oxidizer. In practicing the method, the length of a bore through which the fuel and oxidizer pass is maintained short enough that a sheath of unmixed oxidizer surrounds the combusting mixed fuel and oxidizer, eliminating any need for water cooling. The lengths of torches of the present invention can be significantly shorter than those of the prior art, making the torches well suited for use in confined spaces, and the torches have been found to allow spraying materials at a greater rate than torches of the prior art. The reduced length also facilitates introducing into the passage material to be spray-coated.