20 the pressure drop from chamber 48 to chamber 50 is controlled by flow rate but is affected by roll speed viscosity and gap 40 the material flowing out of header 22 is connected by line 79 to an automatic pressure regulating device preferably in the form of an overflow weir 80 as shown in fig3 an overflow weir 80 is elevated above the level of the applicator 10 to provide a predetermined and desired head and the air laden coating material flows from line 79 into the first compartment 81 through the slot in a v slotted weir plate 82 and down into an outlet compartment 83 and into the return pipe 86 the level of fluid in compartment 81 defines the pressure head in chamber 50 such overflow weirs are well known in the art and fairly accurately control and provide a constant head in the chamber 50 the air laden coating is then returned from the weir chamber 83 through a line 86 to the tank 60 good results have been obtained with a pressure applicator described according to this invention in which the supply cavity 20 feeds into a slot orifice 45 of about 0 020 u2033 in width the small of running chamber 48 at the doctor blade has a dimension of about 0 1 u2033 u00d7 0 1 u2033 the coating then flows against the direction of the roll 25 to the onrunning chamber 50 followed by a slot 55 of about 0 080 u2033 in width and into the second tapered cavity or outlet port 22 the deaerator process and apparatus as defined in 70 in fig2 is preferably positioned downstream of the filters 65 as shown but may be place.