On 11 June 1896 a fire broke out, destroying all the wooden factory buildings, two buildings housing workers, and the warehouses. Only the brick bleaching plant remained. Because the mill was insured and the price trends of cellulose appeared favourable, construction of the new factory was started immediately. The buildings had reached the roofing stage in the autumn of the same year.

The building was designed by architect Bernhard Blom. The technical design was executed by engineer John E. Johansson, son of the founder of the mill. The intermediate floors of the brick-built factory were still made of wood. The plant had capacity for annual production of about 5,000 tonnes. Machinery was ordered mainly from Germany, but three 63 cubic metre boilers manufactured by Tampereen Pellava- ja Rautateollisuus Oy were installed in the boiler house. The factory became operational in the autumn 1898.

Chemical pulp production grew steadily through the early 1900s. Sales of bleached pulp were particularly buoyant, but the Jämsänkoski bleaching plant was so small that only 2/5 of the production could be bleached. Breaking out of the First World War caused difficulties in obtaining sulphur and reduced the quantity of cellulose produced by half. In 1917 the company name was changed to the Finnish form Osakeyhtiö Jämsänkoski.


The Jämsänkoski mill was wanted by United because of the chemical pulp it produced. The founder of the company, General Rudolf Walden, estimated that Jämsänkoski could produce the pulp required by all three paper mills; Simpele, Myllykoski and Jämsänkoski. Reforms aimed at increasing production were designed by Anton Kuhn, a German engineer, together with the mill superintendent, Benjamin Snellman.

The improvement works began at Jämsänkoski in 1920, and because of the large investments, the summer was named the 'million summer'. Many construction projects were launched and a lot of external labour arrived in the area. Expenditure was copious and the renovation works mushroomed out of control. Lack of technical expertise, excessive optimism and lack of supervision resulted in failure of Kuhn's project.