Pressure impregnation (KDI)

We have many products in our range such as carports, patio roofs or children's play equipment, which are made of pressure-impregnated wood. In addition, almost all substructure timbers of our garden houses are made of pressure-impregnated wood. We use the modern process of pressure impregnation for our woods. It is an effective and ecologically sound method for wood preservation. Liquefied impregnating salts are pressed into the wood under pressure and bond with the wood.

In addition to the positive properties such as greater durability of the wood outdoors and resistance to blue stain, fungi or wood-decomposing insects, certain properties may occur with boiler pressure impregnation, such as:

KDI - Cracks

The pressure-impregnated woods are protected against weather and environmental influences and against pest infestation by the above-mentioned process. Cracks in wood treated with KDI can be explained by the swelling and shrinkage behaviour. Unfortunately, due to the drying of the wood, cracking cannot always be avoided. In the case of large and rapid shrinkage, the resulting shrinkage forces can exceed the internal strength of the wood, the wood structure tears and cracks form. However, this property does not affect the stability or durability of the wood. Depending on the weather, these cracks can close almost completely.

KDI mold infestation

If mold growth occurs, it is Ascomycetes (sac fungi) or Fungi imperfecti (incompletely known fungi). The most common species are the Penecillium and Aspergillus species, which belong to the Ascomycetes. Molds feed on ingredients of cut cells and organic impurities ... The molds only grow on the surface of the wood and do not penetrate deeper into the interior of the wood. The strength of the wood is not impaired, only wood discoloration can be caused. After the wood has dried out, the infestation dies and can be removed mechanically using an industrial vacuum cleaner with a fine-particulate filter, or alternatively, washing it off with a 5% acetic acid solution has proven to be a home remedy to combat mould.

Greenish white dots in the course of boiler pressure impregnation

Small greenish/white dots can often be seen on the surface of the woods. Often this is classified as mold at first. However, these are only harmless salt crystals that combine with resin components from the wood on the surface. These dots will disappear over time and become unrecognizable. These salt crystals on the surface are considered a quality feature for careful pressure impregnation.

KDI - Strips (brain edges natural)

Unfortunately, the seemingly natural interfaces cannot be avoided technically. On the one hand, short pieces cannot be pressure impregnated, and on the other hand, wood absorbs the impregnation solution differently due to different cell sizes. The closer the cells are to the nucleus, the less they can absorb the liquid. These interfaces can be repainted by hand afterwards using an impregnation solution.