Six treatments (one control and five decoration coatings) were applied to radiata pine wood treated with micronized copper azole (uCA-C), for outdoor use (R3) at a rate of 3.08 kg/m3 retention (T2). One decoration coating was applied before impregnation treatment: Prestain P (T3), and two, were applied in mixture with the uCA-C preservative Black Cylinder (T5) and Red Cylinder (T4). Two varnish were tested: a water-based varnish (T6) and solvent based varnish (T7). Additionally, untreated radiata pine specimens were tested as a reference (T1). The changes in gloss and color of these five decorative coatings were evaluated after they were subjected to natural aging tests (EN) for three months, and accelerated aging trials (EA) during an exposure to UV radiation of 340nm for 500 hours. In EA treatments changes in gloss and changes in color showed the lowest variation in T3 and T5, and highest variation in treatment trial T4. In EN trials, changes in gloss and color showed their lowest variation in T3 and T5.The costs of each decoration coating were assessed in terms of performance by timber volume to be coated. The lower cost of the three decoration treatments was T3, with a value of US$ 16 m3, followed by T5 with a value of US$.24/m3. Compared to alternative siding products available on the market, such as fiber cement and vinyl siding, coloured treated wood with prestain P is competitive with vinyl siding and 58% lower cost than fiber cement.

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