A method for use in a coating process, the method comprising: pre-heating a substrate in a chamber in the presence of a coating material , wherein the coating material is volatile during the pre-heating; shielding the substrate during the pre-heating from premature deposition of the coating material by establishing a gas screen between the substrate and the coating material ; characterised by : providing the gas screen from at least one first gas manifold near the substrate , wherein the substrate is within a hood within the chamber , the hood including a wall that extends partially around an interior region in which the substrate is located, and the at least one first gas manifold is within the interior region of the hood adjacent the substrate ; thereafter reducing a shielding strength of the gas screen ; and establishing a gas flow from at least one second gas manifold to compress and increase the density of a plume containing the coating material ; wherein the at least one first gas manifold includes a hollow tube having a plurality of apertures arranged along a side thereof, the plurality of apertures being directed toward the substrate and being arranged circumferentially around the tube and axially along the length of the tube . pre-heating a substrate in a chamber in the presence of a coating material , wherein the coating material is volatile during the pre-heating; shielding the substrate during the pre-heating from premature deposition of the coating material by establishing a gas screen between the substrate and the coating material ; characterised by : providing the gas screen from at least one first gas manifold near the substrate , wherein the substrate is within a hood within the chamber , the hood including a wall that extends partially around an interior region in which the substrate is located, and the at least one first gas manifold is within the interior region of the hood adjacent the substrate ; thereafter reducing a shielding strength of the gas screen ; and establishing a gas flow from at least one second gas manifold to compress and increase the density of a plume containing the coating material ; wherein the at least one first gas manifold includes a hollow tube having a plurality of apertures arranged along a side thereof, the plurality of apertures being directed toward the substrate and being arranged circumferentially around the tube and axially along the length of the tube . providing the gas screen from at least one first gas manifold near the substrate , wherein the substrate is within a hood within the chamber , the hood including a wall that extends partially around an interior region in which the substrate is located, and the at least one first gas manifold is within the interior region of the hood adjacent the substrate ; thereafter reducing a shielding strength of the gas screen ; and establishing a gas flow from at least one second gas manifold to compress and increase the density of a plume containing the coating material ; wherein the at least one first gas manifold includes a hollow tube having a plurality of apertures arranged along a side thereof, the plurality of apertures being directed toward the substrate and being arranged circumferentially around the tube and axially along the length of the tube . <EOS>