The invention refers to a method for post-processing of a product, especially paper or paperboard, which has been fabricated at least partly from pulp containing lignin, comprising the following steps: introducing the product into a product gap of a belt press having at least one belt, heating up the product within the belt press to a temperature between 160 C. and 350 C. and submitting the product within the band press to a line pressure between 30 N/mm and 200 N/mm and/or a surface pressure between 50 kN/m.sup.2 (0.5 bar) and 600 kN/m.sup.2 (6 bar), especially between 200 kN/m.sup.2 (2 bar) and 600 kN/m.sup.2 (6 bar).