Photooxidation and darkening of woods
Large scale glass facades and window fronts are popular architectural design elements. Likewise, the use of wood (flooring, furniture, etc.) indoors is increasing. As UV light with wavelengths of 330 to 380 nm passes through window glass, UV light can interact with the wood surface (especially lignin) and trigger chemical reactions (photooxidation). The result is severe, undesirable discoloration and color changes over time, as well as brittleness and wood erosion.
Current UV blocking coatings
In order to counteract the photooxidation and the related darkening of woods, indoor wooden elements such as floor coverings and furniture are often coated. These coatings typically contain pigments to protect the wood from UV light. However, one disadvantage is the loss of the natural appearance due to the highly opaque pigments. Another option is the use of transparent UV blocking additives, such as benzophenones, benzotriazoles or phenyltriazine derivatives. But these are classified as a health hazard. This is particularly problematic as they are volatile substances that can be absorbed through inhalation.
Our new innovation: Bio-based UV blocking coatings
Currently, there is no wood coating available that addresses the problems described above. The goal of the Project ProTann is therefore to develop a sustainable wood preservative that is not harmful to health and is made from natural compounds. The Fraunhofer Institute for Process Engineering and Packaging IVV is responsible for finding suitable plant components for this application. A new type of coating system will be developed for this purpose, providing a good film formation on wood surfaces and containing plant-based UV blockers. The development of the fully formulated coating system in this project is the responsibility of the company Naturhaus Naturfarben GmbH, which specializes in the development of natural formulations for wood finishes.
The product needs to satisfy the following requirements:
- It should be transparent and provide a UV blocking effect
- Good penetration of the formulation into the upper wood layers in order to prevent possible wiping off during cleaning of the respective wood elements.
- High stability