METHOD FOR MARKING PAPER OR BOARD AND MATERIAL MARKED BY THE METHOD

摘要

The publication describes a method of providing paper or board with a marking that cannot be repeated after the paper has been detached from the paper machine and dried. The marking is made by focusing laser energy on the material fibres on the surface of an object in web form, or throughout its thickness. The invention also relates to marked paper or board, which can be manufactured by the method, or to a product that is obtained from the same by further processing.