Abstract: A process for applying a thermoplastic coating to a substrate wherein the gases and other volatiles in a boundary layer between the substrate and the coating are evacuated using a high volume, high velocity air stream which traverses the surface of the substrate to be coated (functioning as an air knife) such that, when the coating is applied, gases/volatiles do not disrupt the coating while:the coating cools and solidifies. The effect of the air knife may be enhanced by heating the substrate and/or by applying a solvent to the substrate. The air knife also cools down the boundary layer of the substrate so that, as the thermoplastic coating is applied, this cooled-down and gas-evacuated boundary layer provides a measure of insulation between the coating and any gases/volatiles which have not been evacuated from the substrate.