Adding colour to pine the natural way
Consumers like wood that is rich in colour. This represents a significant problem for softwood furniture manufacturers because timber such as pine is white and bland in appearance when first sawn. Colour richness comes naturally with exposure to sunlight over time. However, time is not a commodity that manufacturers can afford.
The colouration desired by the consumer has traditionally been achieved by staining with solvent-based coatings, many of which are becoming outlawed by legislation.
Against this background, a research project was carried out which aimed to mimic, and artificially accelerate, the colouration that occurs after prolonged exposure of wood to natural light. The research method involved the exposure of freshly machined Scots pine to varying intensities of light in the ultraviolet spectrum. Exposure times were also varied in order to achieve the best result.
The ultimate aim was to develop a process with both commercial and environmental benefits.
Over a period of 18 months, we examined the possibility of improving the appearance and durability of softwood furniture by subjecting it to ultraviolet light exposure.
As well as replicating the colouration currently achieved by stains in an environmentally acceptable way, benefits included less wasteful, more automated (and therefore less labour-intensive) processing.
A pan-European consortium undertook the FIRA-led project with industrial companies and research organisations from the UK, Ireland, Spain and Germany. Pineology, a Wrexham-based manufacturer of high-quality pine furniture was acting as co-ordinator with Dr Honle of Germany providing UV expertise.
One of the key objectives was to attempt to protect the finished product from further colour change in use. Sonneborn & Rieck, the largest privately owned coatings company in the UK, played a vital role in this task by developing a UV lacquer system compatible with the colouration technology.
Three Spanish furniture manufacturers Galtee of Ireland, Buckinghamshire Chilterns University College and Aidima of Spain were also involved in the project.