The first modern tissue paper machine started production at the Mänttä mill in 1961. Greaseproof paper for baking and cooking was introduced later the same year.
The brand name Serla® was launched on the Finnish market in the 1960s for kitchen towels, handkerchiefs, baking and cooking paper products as well as for toilet tissue.
In 1986, G.A. Serlachius Oy merged with Metsäliiton Teollisuus Oy, a Finnish forest products company, to form a new company named Metsä-Serla.
In 1989, Metsä Tissue acquired Holmen Hygiene, a Swedish tissue paper and hygiene products company, and various restructuring measures were implemented. This acquisition added the brand names Lambi®, Leni® and Katrin® to the portfolio.