Minimising Colour Change
The variation of colour within species is a natural and valuable characteristic of wood, which makes solid wood and veneers much more attractive materials than the products that imitate wood’s appearance.
The adverse effects of exposure to UV light of many items made of natural fibres, wood and plastics, such as: fabrics, carpets, timber products and coatings is well recognized. The fundamental fact is that all articles subjected to UV light change colour and appearance in some way as they age. The only difference being, the amount of change, and the time period over which it happens.
As with all other natural or synthetic materials, the veneers (as well as solid wood) will change colour with time when exposed to sunlight. The degree of colour change varies with the amount of light to which the coating and wood is exposed. Generally, the surface closest to the UV light source is affected more rapidly than that area further away.
The exposure to UV light usually results in a gradual bleaching of red/dark woods and a yellowing of blonde woods. Generally, the application of protective clear coatings containing UV-absorbing additives significantly reduces the detrimental colour change of veneers caused by UV radiation originating from the sunlight exposure.
Research study’s results undertaken by the CSIRO and the University of Melbourne in 2007, funded by Forest and Wood Products Australia (FWPA), revealed that high quality solvent-based acrylic-polyurethane coatings systems with UV blockers (at appropriate percentages) and non-yellowing agents are the most effective protective systems which should be used to protect the veneers against sunlight discolouration. The detailed report on the study “The mitigation of the UV-Driven Discolouration of Reconstituted and Dyed Veneers” can be found on the FWPA website: www.fwpa.com.au
It is important to highlight that generally; the application of protective clear coatings containing UV absorbing additives reduces, but does not completely eliminate, wood discolouration caused by UV radiation originating from sunlight.
Coatings that do not contain the above additives may not offer optimal protection against UV discolouration and it is likely that yellowing and degradation of the coating itself may occur, resulting in higher discolouration compared to the uncoated veneer.
It is essential that you seek technical advice from coating companies, such as Akzolux and Mirotone, on UV protective coatings which are most appropriate for your veneers and veneered products.
For more technical data see the Technical Brief on Minimisation of Colour Change of Reconstructed and Retoned Veneer on the Publications page.