Abstract: A seal disposed in the interior of a roller which is used in a system wherein paint is supplied under pressure to the interior of the roller consists of porous resilient filter material which simultaneously performs the function of sealing the exterior opening which must be present to permit rotation and assembly of the roller parts, filtering pigment from the paint so that if any leakage does occur only non-pigment containing liquid will exit, and permitting relative rotation of rotatable parts of the roller with respect to stationary parts of the roller while maintaining the seal. The seal is in the form of a grommet or elongated washer which completely surrounds a shaft support carried on a rotatable part of the roller to which the paint-applying knap is affixed, the support in turn receiving a shaft of a stationary part of the roller to which paint is supplied under pressure in the interior of the roller.