Method and apparatus for manufacturing watermarked paper

A method for manufacturing watermarked paper, comprising at least one watermark constituted by one or more light regions which have a lower density of fibers and one or more dark regions which have a higher density of fibers, by way of at least one mould cylinder covered with a mould cover which comprises wires which define voids between them and which is adapted to modulate the density of fibers that are deposited on the mould cylinder, so as to produce said light regions and said dark regions in the paper, which comprises:

• a step of forming the mould cover, in which one or more light areas adapted to produce said light regions in the paper and one or more dark areas adapted to produce said dark regions in the paper are produced in said mould cover;
• a step of deposition, in which the fibers are deposited on said mould is cylinder covered with said mould cover which was formed previously in said step of forming the mould cover, so as to provide said watermarked paper;
• wherein, during said step of forming the mould cover, said one or more light areas are provided by locally modifying the permeability of the mould cover by way of an additive process through which material is added to a plurality of said wires of the mould cover, thus reducing the size of a plurality of voids that are defined between said plurality of wires.