Abstract: In a size applicator in which size is circulated between a reservoir tank and an applicator tank from which the size overflows back into the reservoir tank, the squeezing pressure applied to the traveling textile substrate is regulated in response to a sensing of the speed of the substrate. A secondary regulation is applied as a function of sensing of the volume of the size being in comparison with the substrate speed. This sensing of the volume of the size being consumed is accomplished by a hydrostatic sensor in the reservoir tank, the output of which sensing is applied to a microprocessor that compares the signal from the size level sensor with the signal from the tachometer that senses the substrate speed, and upon the comparison exceeding a predetermined tolerance, a further regulation is applied to the piston-cylinder mechanisms that control the squeezing pressure between squeeze rollers and between an emersion roller and the bottom squeeze roller.