A method of increasing the resistance to internal pressure of a glass container comprising the steps of: directing a first mixture comprising a precursor of silicon oxide and a first carrier gas to the surface of the container, thereby to deposit a layer comprising an oxide of silicon on the glass and directing a second mixture comprising one or more precursors of tin oxide and a second carrier gas, which may be the same or different from the first carrier gas, to the surface of the container, thereby to deposit a layer comprising tin oxide on the oxide of silicon wherein the first mixture comprising a precursor of silicon oxide and a first carrier gas is directed to the surface of the container by: arranging a tunnel on a conveyor belt such that the conveyor belt transports the glass container from an upstream end, at which articles enter the tunnel, to a downstream end, at which articles exit the tunnel, the tunnel having a top and first and second sidewalls; a linear array of nozzles, arranged on at least one side wall to deliver a jet of gas, which jet traverses the path of articles conveyed through the tunnel; at least one exhaust aperture arranged on a sidewall, the exhaust aperture being located closer to the downstream end than the linear array of nozzles and means for applying a negative pressure to the exhaust aperture; and further providing an evaporator comprising a heatable tube; directing a carrier gas stream through the evaporator to one or more of the nozzles; introducing the precursor to silicon dioxide to the carrier gas stream in the evaporator and introducing a diluent gas to the carrier gas stream after it passes from the evaporator and before it reaches the one or more nozzles. directing a first mixture comprising a precursor of silicon oxide and a first carrier gas to the surface of the container, thereby to deposit a layer comprising an oxide of silicon on the glass and directing a second mixture comprising one or more precursors of tin oxide and a second carrier gas, which may be the same or different from the first carrier gas, to the surface of the container, thereby to deposit a layer comprising tin oxide on the oxide of silicon wherein the first mixture comprising a precursor of silicon oxide and a first carrier gas is directed to the surface of the container by: arranging a tunnel on a conveyor belt such that the conveyor belt transports the glass container from an upstream end, at which articles enter the tunnel, to a downstream end, at which articles exit the tunnel, the tunnel having a top and first and second sidewalls; a linear array of nozzles, arranged on at least one side wall to deliver a jet of gas, which jet traverses the path of articles conveyed through the tunnel; at least one exhaust aperture arranged on a sidewall, the exhaust aperture being located closer to the downstream end than the linear array of nozzles and means for applying a negative pressure to the exhaust aperture; and further providing an evaporator comprising a heatable tube; directing a carrier gas stream through the evaporator to one or more of the nozzles; introducing the precursor to silicon dioxide to the carrier gas stream in the evaporator and introducing a diluent gas to the carrier gas stream after it passes from the evaporator and before it reaches the one or more nozzles. arranging a tunnel on a conveyor belt such that the conveyor belt transports the glass container from an upstream end, at which articles enter the tunnel, to a downstream end, at which articles exit the tunnel, the tunnel having a top and first and second sidewalls; a linear array of nozzles, arranged on at least one side wall to deliver a jet of gas, which jet traverses the path of articles conveyed through the tunnel; at least one exhaust aperture arranged on a sidewall, the exhaust aperture being located closer to the downstream end than the linear array of nozzles and means for applying a negative pressure to the exhaust aperture; and further providing an evaporator comprising a heatable tube; directing a carrier gas stream through the evaporator to one or more of the nozzles; introducing the precursor to silicon dioxide to the carrier gas stream in the evaporator and introducing a diluent gas to the carrier gas stream after it passes from the evaporator and before it reaches the one or more nozzles.