The present invention concerns a filling matrix for use in connection with a filling apparatus, where an item with a given cross-section is moved through a first opening, through a filling mass and subsequently through the filling matrix, where the filling matrix has an aperture with a cross-section substantially corresponding to the cross-section of the item, where the automatic filling apparatus is preferably used in connection with an automated surface treatment facility. The invention furthermore relates to a method for adjusting such a filling matrix. The filling matrix is made up of at least one clamping plate, preferably two clamping plates, and with at least one replaceable matrix plate which is resilient, and which is clamped between two clamping plates or between a fixed machine part and a clamping plate.