Novel color stabilization concepts for decorative surfaces of native dark wood and thermally modified timber

• Discoloration of dark wood is due to photoreactions of extractives.
• Respective effects are mainly caused by visible light.
• Conventional light protecting systems could intensify photobleaching of dark wood.
• Novel stabilizing basecoats exhibit improved light protection of dark wood.

UV and visible light exposure of dark colored wood and thermally modified timber (TMT) is strongly connected with discoloration and photobleaching of the respective wood surfaces. Conventional and nanoscale UV absorbers as well as radical scavengers (HALS), mainly effective for the protection of softwood and bright hardwood, were found to be improper for the light stabilization of dark wood surfaces. In the current work discoloration mechanisms are discussed considering the role of wood extractives and the sensitivity of dark colored wood types to visible light and results are presented which were obtained by applying novel protecting systems for the light stabilization of transparently coated surfaces from dark colored wood types and TMT.

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