Abstract: A running length of plastic film is processed by submerging a bight of the film in a bath of treatment liquid and drawing the film longitudinally therethrough by a pair of pinch rolls mounted closely adjacent and parallel to the top surface of the treatment liquid. The pinch rolls mechanically remove adhering droplets of the treatment liquid from the film as it emerges from the bath to thereby prevent non-uniform treatment. The film is washed as it emerges from the nip of the pinch rolls by flowing a rinsing liquid into the exit nip and along the axes of the rolls, and means are provided to prevent mixing the rinsing liquid with the treatment liquid. A property of the treated film, e.g., its light transmissions is continuously monitored and the time of submersion of the film in the treatment liquid is varied in accordance with the monitored property to assure uniform treatment.

Abstract: A running length of plastic film is processed by submerging a bight of the film in a bath of treatment liquid and drawing the film longitudinally therethrough by a pair of pinch rolls mounted closely adjacent and parallel to the top surface of the treatment liquid. The pinch rolls mechanically remove adhering droplets of the treatment liquid from the film as it emerges from the bath to thereby prevent non-uniform treatment. The film is washed as it emerges from the nip of the pinch rolls by flowing a rinsing liquid into the exit nip and along the axes of the rolls, and means are provided to prevent mixing the rinsing liquid with the treatment liquid. A property of the treated film, e.g., its light transmissions is continuously monitored and the time of submersion of the film in the treatment liquid is varied in accordance with the monitored property to assure uniform treatment.