the invention relates generally to an apparatus and method that enables a very accurate initial setup of the coating gap for slot die coater and subsequent control of the coating gap during coating operations such that web splices and web defects do not interrupt the coating process . an highly accurate initial set up is achieved via the use of a tapered or wedge - shaped adjustment member mounted perpendicular to the axis of travel of the coating head where the movement of this tapered or wedge - shaped adjustment member in a direction perpendicular to the axis of travel of the slot die housing adjusts the coating gap in increments on the order of ten microns . substrate splices and defects are detected prior to reaching the coating position such that a feed - forward controller is able to momentarily retract the coating head both avoiding slot die damage and avoiding interruption of the coating process , yet the apparatus is able to return the coating head , with high precision , to its prior position once the splice or defect has passed .