First chemical pulp mill to 1896

The pulpwood required by the factory was initially cut from the forests of Sahala farm owned by the company. The logs from further afield were floated to the mill. Preparation of the raw wood brought straight from the forest was a time-consuming stage. 20 men were needed merely for the hand-debarking of the logs.

The debarked logs were brought into a heated drying room and placed on beams, bringing the resin to the surface. Once dry, the logs were soaked in water and then lifted into the cleaning shelter, where the resin and other impurities were scraped away. After this, the logs were taken to the sawmill and sawn into boards. The knots were removed by hand-drilling, and the boards were taken into a small two-bladed chipper. The resultant chips were lifted in a splint basket up to the chip loft and cleaned once more. The cleaning was done by women, who picked out the knots and litter form the piles of chips poured out on huge tables. Only now were the chips clean enough to be shovelled into the silos over the boilers.

Floor plan of the old pulp mill. Drawing based on information given by A. Laulainen in 1939.


The pulping liquor of sulphite cellulose was calsium bisulphate. In preparation of the cooking acid at Jämsänkoski, in common with other early sulphite works, the so-called Frank's lime milk system was used. The lime milk, made from limestone, was combined with sulphur dioxide made in sulphur burners. The strength of the finished mixture was 12 degrees Beaume (measure of concentration of solutions). For the actual cooking, the solution was diluted with water.

Pressure was raised to 5 atmospheres, when the air was released from the boiler. Cooking took 12 -14 hours, and the final temperature rose to 140 - 145 degrees Celsius. At the end of cooking, samples were taken from the test valve, and the pulp was visually assessed. Finally, the boiler was gassed, and the pulp emptied with low pressure into the pulp container.

The gases created during cooking were released directly outdoors. The gases emitted from the boiler house and acid section were so powerful that almost all vegetation near the factory died. Because there was no recovery of the gases, sulphur consumption grew very high relative to the quantity of cellulose obtained.

Post-processing of pulp

The pulp containers were large boxes built of wood alongside the boiler house, and the pulp was rinsed in the boxes by spraying water from a hosepipe. There were holes in the bottom of the containers, through which the lye and washing water drained away. From the pulp container the rinsed pulp was carted onto the pulp platform, from where it travelled through the separator, sand table and sieves, by which time it had been cleansed of most impurities. The purity of the pulp was very important, and the cleaning was done mostly by hand. This laborious hand-cleaning continued until the turn of the century, when mechanical knot separators become common in pulp mills.

Only the brick-built bleaching plant remained of the old pulp mill after the fire. Men loading carts that were pushed along tracks at the turn of the 1900s.Finally, the pulp was driven to the drying or collector machine. First on the machine was the pulp collector roll, from the surface of which the pulp was removed onto a felt and from there through two rollers onto three drying cylinders. At first, there was no cutter on the machine, so the cellulose was run onto rolls. But they began to go mouldy, and the rolls had to have holes drilled for ventilation.

After the advent of the cutter, the cellulose was cut into sheets. At sorting tables, women checked the sheets once more, and the last of the litter and impurities were picked off. Finally the sheets were weighed and packed in 10 poud (16.4 kg, old Russian weight) batches which were compressed in the baling presses into tight bales. The bales were wrapped in jute cloth, tied and equipped with the factory’s quality mark and batch number. The product was ready for the market.