With the wet-end improvement in its UPM Pietarsaari mill last year, the formation of the paper improved up to 30 percent for machine finished grades. The strength improved up to 15 percent for sack paper grades. The improvement was made to answer to the needs of the market. “Our sack paper customers needed a stronger and better performing paper, and by this improvement we can now produce what they need,” says Jussi Toikka, Vice President of Converter Segment, UPM.UPM is continuously finding new sustainable products to better serve new packaging market needs. The ongoing development is in the field of a new type of online barrier coated paper, tha company writes in a press release.