A method and apparatus are described for coating a substrate such as glass with a powder such as a compound that can be decomposed by heat. The method comprises the steps of forming a sheet of powder suspended in a gas moving toward the substrate to be coated, homogenizing the mixture of powder and gas by creating turbulences in it, and accelerating the sheet in the direction of the substrate with flowing gas having greater velocity than that of the sheet. This method and the apparatus which implements it are particularly useful in the manufacture of glass coated with a film such as metal oxide.