When exposed to light, wood products react by fading, darkening or changing to a different colour. The stronger the light, the more pronounced the colour change. Timber veneers are no exception, writes Timber Veneer Association of Australia’s (TVAA) technical representative Peter Llewellyn.
The effect is seen where pictures hang on timber panelled walls, or mats are placed on timber floors. The exposed surface changes while the covered area retains its original appearance.
It’s ultraviolet that causes the change. The effect of UV light on wood can be masked by applying a colour stain, or blocked with a pigment stain, but often it’s preferred to try to keep the original appearance. Apart from protecting wood surfaces from sunlight by shading windows, the best option is to apply a coating with UV absorbers. These are marketed as additives, which are mixed into commonly available coatings to filter out UV radiation.
A collaborative research study into UV discolouration was undertaken several years ago by the Decorative Wood Veneer Association (forerunner to the TVAA), CSIRO Manufacturing and Materials Technology and the University of Melbourne.
The aim was to investigate the discolouration of selected veneers when exposed to UV light and the effectiveness of various coatings currently used by the industry to maintain colour stability. The project was financially supported by the Forest and Wood Products R&D Corporation.
The outcomes of the research project are summarised in a technical brief, available on the Timber Veneer Association’s website here: http://timberveneer.asn.au/referencematerial/publications – refer to the heading Minimisation of Colour Change of Reconstructed and Re-toned Veneer.
The TVAA recommends the use of UV absorbing finishes on all veneered surfaces, not just those exposed to strong, direct sunlight. On less exposed surfaces similar changes may occur, but more slowly, so UV absorbing finishes are an advisable precaution.
As TVAA’s technical representative, Peter Llewellyn brings a wealth of knowledge and experience with timber veneers and provides unbiased technical advice on a range of issues related to our much-loved beautiful, natural and unique veneers.
Matilda Veneer is a proud member of the Timber Veneer Association of Australia. Matilda’s own Anthony Wardrop currently holds the role of vice-president of the Association.