White cloud discoloration

What is white cloud discoloration?

White cloud discoloration is an undesirable phenomenon that can occur when drying wood, especially oak. It manifests itself as uneven, cloud-like light spots on the surface of the wood. This discoloration usually occurs when the wood is dried too quickly or unevenly, resulting in different moisture zones. The risk is particularly high when drying in closed kilns without prior air drying, as the wood cannot release moisture evenly.

White cloud discoloration | Photo © by Hugo Kämpf

Drying and white cloud discoloration

In order to prevent the so-called white cloud discoloration, we always pre-dry our oak wood from a thickness of 40 mm carefully and for a sufficiently long time in the air. This is always done under cover to protect the wood from drying too quickly in the sun and wind.

This gentle pre-drying ensures that the wood achieves its outer stability evenly and is evenly colored in a natural process over two summers and two winters. This method produces high-quality wood that is free of cracks and has a uniform color. This makes it possible to cut lamellas that are absolutely identical in color.

This is followed by technical drying in our drying chambers.

Cut thicknesses over 40 mm are usually technically dried under vacuum. Here we control the climate in the closed system in order to achieve the desired final moisture content for flawless processing.

The residual moisture content is 8 - 10 % wood moisture.

A uniform color is achieved with professional wood drying | Photo © by Hugo Kämpf

To summarize - simply explained

White cloud discoloration is an uneven light stain on wood that can occur if drying is too fast or uneven. To avoid this, oak wood is slowly air-dried under cover. This process ensures uniform coloring and stability of the wood, which ultimately results in high-quality, crack-free wood that can also be further processed for visually uniform slats.