In a painting operation, a method for controlling the viscosity of a coating composition wherein said coating composition is a sprayable mixture, said method comprising the steps of: producing a first atomized stream of a first coating component of said coating composition through an orifice of a spray gun with a stream of a pressurized carrier, wherein said first coating component is stored in a first storage container and conveyed through a first inlet of said spray gun to said orifice, wherein said first coating component is a mixture of a crosslinkable component and a crosslinking component, which are chosen in such a way so as to control the viscosity of the first coating component, and wherein the viscosity of said first coating component increases in a period of 8 hours less than 40% prior to being conveyed through said first inlet; producing a second atomized stream of a second coating component of said coating composition, wherein the second coating component comprises one or more materials selected from a catalyst, an initiator, an activator or a combination thereof, wherein the second atomized stream is produced by siphoning the second coating component with a siphoning stream selected from the first atomized stream of the first coating component, the stream of the pressurized carrier, or a combination thereof, from at least one delivery outlet coupled to a second storage container containing said second coating component, said delivery outlet being positioned at said orifice; optionally, regulating the supply of the second coating component to said delivery outlet by coupling a regulatory device to said delivery outlet; intermixing the first atomized stream and the second atomized stream to form a coating mixture; and applying the coating mixture on the substrate to form the layer of said coating composition thereon. producing a first atomized stream of a first coating component of said coating composition through an orifice of a spray gun with a stream of a pressurized carrier, wherein said first coating component is stored in a first storage container and conveyed through a first inlet of said spray gun to said orifice, wherein said first coating component is a mixture of a crosslinkable component and a crosslinking component, which are chosen in such a way so as to control the viscosity of the first coating component, and wherein the viscosity of said first coating component increases in a period of 8 hours less than 40% prior to being conveyed through said first inlet; producing a second atomized stream of a second coating component of said coating composition, wherein the second coating component comprises one or more materials selected from a catalyst, an initiator, an activator or a combination thereof, wherein the second atomized stream is produced by siphoning the second coating component with a siphoning stream selected from the first atomized stream of the first coating component, the stream of the pressurized carrier, or a combination thereof, from at least one delivery outlet coupled to a second storage container containing said second coating component, said delivery outlet being positioned at said orifice; optionally, regulating the supply of the second coating component to said delivery outlet by coupling a regulatory device to said delivery outlet; intermixing the first atomized stream and the second atomized stream to form a coating mixture; and applying the coating mixture on the substrate to form the layer of said coating composition thereon.