Increasing the use of wood in construction, for example, is not unproblematic. Factors like moisture and sunlight are harmful to wood, and it needs to be protected.
Traditional protective agents have been non-renewable chemicals, some of which are toxic. Better options have been developed, though they are often detrimental to the strength of wood, among other things.
Coatings generally used to protect wood, concrete, metals and composites are oil-based. They often contain substances that are harmful to the environment.
Coatings based on vegetable oils derived from pine, flaxseed, coconut, soybean or castor bean may be environmentally more sustainable , but are often not resistant to wear. They are therefore often combined with synthetic materials.
Similarly, volatile hydrocarbons often used in coatings are a health risk, and they are also harmful to the ozone layer. The European Union has restricted the use of certain chemicals used to manufacture protective coatings.
Researchers at the School of Chemical Engineering of Aalto University have developed a coating for wood that is made of components contained in wood. Wood consists of cellulose, hemicellulose and lignin. The new coating agent was developed from lignin.
The wood-based coating is safe, low-cost and high-performing. It preserves the natural structure and texture of wood surface. It is water-repellent and protects against both stains and the discolouration caused by sunlight.
’The coating also preserves the breathability of wood very well,’ says Alexander Henn, Doctoral Candidate at the School of Chemical Engineering of Aalto University,
As a coating, lignin has many advantages over coatings in current use. It prevents corrosion and freezing very well, and protects against bacteria and ultraviolet radiation.
’Next, we will study how to make the coating more elastic,’ says Professor Monika Österberg from Aalto University.