A process for the uniform wetting of threads, particularly artificial threads wherein the wetting liquid issues under pressure from a narrow orifice of a nozzle and the thread passes directly over the orifice or over an edge below the orifice. The rate of transmission of the liquid to the thread is controlled either by varying the pressure at which the liquid is supplied or by adjusting the resistance to the flow of the liquid through the nozzle. The liquid is supplied through a pipe a provided with a manometer f and with branches b. Each branch b is provided with a nozzle c against which the thread passes on its way to a spool e or to some similar collecting device. In one form of nozzle, as shown in Fig. 4, the thread passes over the orifice g from which the liquid issues under pressure and the front of the nozzle is notched to prevent the thread from leaving the nozzle. A modified form of nozzle, as shown in Fig. 7, contains a cylinder i, provided with a bore g and adapted to be exchanged for a similar cylinder with a bore of different diameter. In this case the liquid flows from the orifice to an edge k below the orifice and is stripped off from that edge by the thread.