Abstract: The present invention concerns a process for producing a paper or board product, which process comprises providing a furnish comprising fibers; subjecting a first portion (1) of the furnish to polymer treatment, in which polymers are added to the furnish in at least two steps; blending said polymer treated first portion with an untreated second portion (2) of the furnish; and dewatering the furnish on a wire to form a fiber web. By treating only a portion of the furnish, the strength of the resulting paper or board product is significantly improved whereas the bulk remains substantially unaffected. The invention also concerns a paper or board product produced according to the process.

Abstract: The present invention relates to a process for obtaining retention of the manufacture of paper, whereby one adds a cationic, high polymer polysaccharide at the preparation of a stock of paper pulp; that one adds an anionic aluminium compound, or a combination of an aluminium salt and an alkali or an acid to the formation in situ of such an anionic aluminium compound immediately prior to the head box, whereby pH immediately prior to the head box is kept at pH 7 to 8.