Wood is a natural product with a number of natural properties. These properties are no reason for complaint, but are inherent in the use of a natural product.
1. Checking, twisting and warping
Checking (cracks) caused by drying are natural features of wood and do not affect its durability. The structure of the wood may cause it to warp and twist during the drying process. Wide parts with a relatively thin cross-section are more likely to warp and twist.
2. Knots and growth rings
Knots and growth rings are a part of the natural structure of wood. They can appear in various forms, depending on the type and age of the wood.
3. Rough surfaces
All products are sawn. Inaccuracies and roughness can occur where the grain twists around knots.
4. Green spots
Green spots are a natural phenomenon caused by the reaction of the treatment agent with the natural resin in the wood.
5. Stains and cyanobacteria
Stains and cyanobacteria may develop from improper storage of products (relative humidity higher than 18%).
Discoloration is caused by sunlight. The wood will discolour to a certain extent after the treatment process, because direct sunlight affects the wood. The wood structure can also cause discoloration. In coniferous species, the colour of the treatment agent shows up differently in sapwood and heartwood.