Wood working19.10.2018

Sawn timber processed on the painting line according to the customer’s wishes

Timber to be painted is usually brought to the painting line directly from the planing mill. Storage times are kept as short as possible.

Timber to be painted is usually brought to the painting line directly from the planing mill. Storage times are kept as short as possible.

Koskisen employee Argo Vinkman gives us a glimpse into the operations of the mill’s painting line. Argo’s job as the painting line’s first-line supervisor includes both production planning and placing paint and supply orders. He has worked at Koskisen for eleven years, several of which on the painting line.  

Agile painting line serves internal customers 

Two people work on Koskisen’s painting line per shift, but this can be changed according to need. Weekday morning shifts are the norm. “If it appears that there is a need for more or there is a rush, there can be three shifts,” explains Argo. “In processing, we have quite a lot of multi-skilled employees, so they can work at different stations If the situation calls for it, we can therefore have even triple the number of employees working.” 

The painting line strives to get boards from the planing mill to the painting line quickly and directly. The location of the processing lines all in the same mill area makes things easier. “Storage times are short, and the internal customers feed the processes. This is a clear benefit for us in the markets.Everything is produced under the same roof: chipboard, plywood products, processed and further-processed products,” says Argo. According to him, there are quite few operators in Finland who process wood to the extent that Koskisen does. “Since all of this happens on the same lot, we are able to react quickly to orders and production needs,” Argo adds. 

The painting line was established in 2009 in the old planing hall, and it was built partly around old machinery when the new high-efficiency planing mill replaced the old planing mill. Painting operations were outsourced for roughly a year while the painting line was being built. On the painting line, exterior cladding boards from the planing mill are processed in a range of sizes, from the traditional 20 mm products to a max. of 48 mm all-round planed products. “It’s a broad scale. Today, for example, we were processing 34 millimetre boards,” recounts Argo.  

Last year, as much as 19,000 cubic metres of painted products came out of the painting line. “The volume this year will be slightly less, closer to 11,000 cubic metres, as we have streamlined our operations by eliminating products that are less favourable for us,” says Argo. The painting line has its own internal quality control guidelines, in addition to which, an external auditor inspects the painting line’s processes once a year.

A planed board moves along the line towards the vacuum coater.

A planed board moves along the line towards the vacuum coater.

Precise work and minimal waste 

When the sawn timber arrives from the planing mill, it is gently unloaded onto a table using a vacuum lifter. The feed operator then places it at the feeding end of the line. The sawn timber is painted using a Makor vacuum coater. “The paint is fed to the coater from a large container or, for smaller batches, it can be dosed even in individual cans.” 

The vacuum coater doses the paint in a web-like pattern on the surface of the planed board. Even and efficient spreading means less paint is wasted.

The vacuum coater doses the paint in a web-like pattern on the surface of the planed board. Even and efficient spreading means less paint is wasted.

The vacuum coater spreads the paint in a web-like pattern on the board’s surface, and the spraying takes place inside the painting unit. On both ends, the opening is shaped like the board being painted, enabling precise dosing of the paint. “This machine is well suited to painting exterior cladding products. No paint is wasted, and the painting result is very consistent,” says Argo. The painting line mainly produces products with a primer coating. All the paints used are Teknos’s water-based paints. “We have many years of solid co-operation behind us,” says Argo.  

Primer protects the wood 

The painting line uses all of the most common colour charts, and the paints can be tinted on the painting line’s own machine. “The advantage of having our own paint mixer is that the paint amounts are very precise. We used to order ready paint colours from the factory, but the way we do it now makes more overall economic sense,” explains Argo.  

The painting line most often paints the boards with a white primer, however. The purpose of the primer is to protect the wood. Primer also means there is less need for the final paint, as a board that is properly primed does not require as many subsequent coats of paint. 

Being able to quickly process a board works especially in the end user’s favour. When wood is painted as soon as possible after planing, the wood cells are still open, which gives the best paint adherence. The final painting is usually carried out at the construction site, after the boards are installed. Intermediate painting is also possible, in which case the end user is only required to take care of the last stage, i.e. the final coat of paint.  

The painting line also processes fire-rated exterior cladding for demanding sites, such as nursing homes, day-care centres and apartment buildings. “This is Teknos’s own treatment, and a product that is made in compliance with regulations. In essence, it is a product that has been painted several times, which means the required fire rating is achieved with a sufficient number of coats. The end result is a CE-marked and controlled product,” says Argo. 

A painted and dried panel is stacked and awaits packaging according to the customer’s specifications.

A painted and dried panel is stacked and awaits packaging according to the customer’s specifications.

After painting, the planed and painted sawn timber is dried and packaged 

After it is painted, the piece of timber enters the drying chamber. Water-based paint takes 5 to 15 minutes to dry in a 45-degree Celsius drying chamber. The idea behind the drying chamber is that the water evaporates from the paint, resulting in a board that is dry to the touch.  

After drying, the board is stacked. “A primed board can also be stacked when wet, as the boards will not stick together. The consistency of the paint used for intermediate and final coatings is such that the boards cannot be stacked if the paint is wet,” explains Argo.

The painted planed timber packages are ready to go to the customer or to storage.

The painted planed timber packages are ready to go to the customer or to storage. 

Stacking takes place according to the customer's specifications. “The packages are usually protected with a plastic hood that covers five sides of the package. Alternatively, the pieces inside the plastic hood can also be shrink-wrapped in smaller bundles. After that, the product is ready to be shipped out or moved to storage,” says Argo. 

The painting line does not have direct consumer sales; these customers receive their products through hardware stores. Most of the painted spruce boards are, however, efficiently delivered to Koskisen’s pre-fabricated house factory. 


Get to also know other articles about sawn timber production:

Sawing: Scent of resin in the air at the sawmill
Drying sawn timber: Drying sawn timber in chamber and progressive drying kilns
Sawn timber planing: Sawn timber planed smooth and profiled at the planing mill