Care and protection of wood

As recently as 30 years ago there was practically no special consideration given to paints for use on wood. Before 1939 oil-based paints were used for most purposes and lead-based primers were in common use on joinery.

Changes in paint composition in the post-war period led to a changed failure mode for paint on wood surfaces and to an increase in the problems coming to the notice of research workers. Changes in the properties of the materials used for building and in building practice and design led to an increase in the risk of wood becoming wet. This meant not only a higher risk of decay but also greater demands on the finish (whether paint or varnish) particularly in terms of elasticity and adhesion.

In the mid 1960s the then Forest Products Research Laboratory (now the Princes Risborough Laboratory) and the Paint Research Association began programmes of research on problems of finishes on wood. There gradually emerged a realisation that the formulation of a decorative and protective finish with a reasonably long life was a new problem which posed a challenge for wood scientists and paint technologists. The problems to be overcome are now well understood even if they are not fully solved. They are important because of the need to contain the ever increasing costs of building maintenance.

To devise a satisfactory finishing system it is necessary to recognise the complex character of the substrate the interaction of the substrate with the finish and the environment in which the product is to be used. There is for example a growing recognition that the requirements for an internal and an external paint are different.