History5

Board production

Sheets of board were manufactured from groundwood pulp, the source of which was spruce trees. Many of the phases of board production required a high level of precision, and many phases in the production of the sheets were done by hand. 

5.1

Raw material 

The 4-metre-long logs were hoisted out of the water with a horse winch until the very last day of operation in the summer of 1964. In the early years of the mill, a wooden pulley powered by humans was used. 

Pulpwood was stored along the track running from the lift to the mill. Carts of wood were pushed to the mill by workers until the 1920s, when horses were finally brought in to help. In the groundwood mill, the logs were cut into pieces 50 or 60 centimetres long, mechanically debarked until clean and white, and transferred to the grinders. 

5.2

From groundwood pulp to sheets of board 

Groundwood pulp was produced mechanically at Verla by rubbing the wood against a grindstone. A single machine could grind about 15 cubic metres of wood per day. The grinders were located upstairs in the mill, and the pulp, mixed with water, travelled down the sluice and through the pulp cleaners to the forming machines below. 

The ready groundwood pulp was directed downstairs to the eight forming machines, which produced 70 x 100 cm sheets. Depending on what had been ordered, the same machine could be used to produce thinner or thicker boards. 

The most important section of the board mill was the machine hall, where the actual production of board sheets and market pulp took place. The production methods were similar, but the pulp intended for sale was left moist and packed in bales of 200 kilograms. The manufacture of board, on the other hand, required several more steps. The board was said to be handmade, as people handled the sheets in 14 different phases of production. 

One of the most difficult phases was cutting the moist board strip and removing it from the forming machine’s rotating roller. When the layers of pulp achieved the desired thickness, the metallic bell on the side of the machine started to ring. This informed the machine operator that the board had to be quickly removed from the cylinder. The removal was done with a sharpened juniper stick.

Heavy bundles of sheets were transferred to the press at the back of the hall, where excess water was removed from the sheets. After that, the sheets were ready to be transferred to the drying loft, which was a separate building next to the board mill. 

5.3

The drying loft 

Female workers hung the damp sheets one by one in the drying loft and collected the sheets when they were dry. The sheets of board dried in the loft in about three days, after which they were ready for finishing. When the sheets were drying, the temperature in the loft could rise to 75 degrees Celsius. The heat was not turned on when workers were present, but the drying loft was nevertheless a warm place to work. 

Board could also be air-dried in the summer drying barn at the mill, which was constructed due to the cost of heating. Spaces were left between the wallboards so that the open air could dry the sheets. During sunny weather, the thinnest varieties of board would dry in a few weeks. Compared to the other drying loft, the summer drying barn was a cool and pleasant place to work, and it was nicknamed “the villa”.

5.4

Board finishing

During the cardboard finishing process, each sheet was inspected, weighed and sorted. When they were weighed, the sheets were given a gauge number, which indicated how many sheets would be required for 50 kilograms of board. The mill generally preferred to receive orders for gauge numbers 50–120, but thicker and thinner grades from 30 to 300 were also made, if needed. The work was precise and required some strength, as most of the sheets weighed between 0.5 and 1 kilogram. 

Depending on the customer’s needs, the edges of the sheets were trimmed with a guillotine and the sheets were glazed in a glazing machine. Before glazing, any pieces of wood were removed from the board with a knife. When the sheet was rolled between the cylinders of the steam-heated glazing machine, the surface of the board would be compressed and it would gain a slight sheen. 

5.5

The mill’s board heads out into the world 

The last phase of work was packing the sheets. Typically, the mill produced 200-kilogram bales. The bales of board were transported first by horse and starting in 1929 by truck from the mill to the nearby Selänpää railway station. Board for export travelled by train to the harbour in Kotka. At the mill’s peak, the quality board produced in Verla was exported to about 30 countries. Until 1918, the mill’s main market was in Russia. Afterward, cardboard was exported to Europe and even to the United States. 

A variety of packaging materials were produced from Verla’s board, including cigarette packs, boxes for candy and shoeboxes. In addition to packaging factories, book binders were also important customers.

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