Drying: the heart of the process
Drying the wood is one of the most delicate processes. This is where wood flooring production demonstrates major similarities with the cultivation of other natural materials, where the end result has a massive impact on quality and price: look at wine or coffee, for example.
Drying is not something that can be forced. Different wood species require different drying times. The dimensions and moisture content of the wood before drying play important roles. Drying wood is a science in itself. Kährs uses two drying techniques, with experts in the R&D department working constantly to refine and improve our drying techniques.
“Drying is the most critical of our processes. If we don’t do that job properly, it will have consequences further down the production chain. With engineered flooring, we have to maintain the right moisture balance between the core lamellae and the surface. If we fail to achieve that balance, the boards will end up concave or convex,” explains Torbjörn Lagesson, Production Manager at Kährs.
We’ve done a lot of air drying over the past years, ensuring good quality. We cannot change the laws of nature!Torbjörn Lagesson, Production Manager at Kährs sawmill
Cannot change the laws of nature
After sawing, the moisture content can be as high as 90%.However the surface layer of each of the boards has to have a moisture content of 6% when they are fitted together.
“We test the wood before, during, and after drying so as to ensure its quality before sending it on,” says Torbjörn, explaining that air-drying is often preferable as it results in less cracking and discoloration.
“We have done a lot of air drying over the past years, ensuring good quality. It is hard to replicate the same air drying effect with fresh drying. We cannot change the laws of nature!”
In Sweden, air drying is possible only from late March until Midsummer. The climate is often too humid or too cold at any other time of the year. “Air-dry” means a moisture content of less than 20% in the wood.