Commercialisation of a low-maintenance transparent coating is expected to assist wood products to maintain residential market share in the face of competing materials and potentially expand market share in recreational and non-residential applications. Testing of a range of commerical products had identified one outstanding performer and arrangements were made to work with the developer of this coating to further improve its performance, targeting a 15-year life under Canadian conditions. A series of exposure tests were set up to evaluate potential improvements in resistance to UV and to black stain fungi. This report covers the initiation of a test of the second generation of UV protectant pre-treatments and biocide combinations. It also evaluated the apparent beneficial effect of a supposedly inert formulating agent. UV protectant combinations were tested under a water-based two-step transparent coating and under a water-based clear exterior urethane. The biocide combinations were used as pre-treatments and incorporated in steps one and two of the water-based two-step transparent coating. After six months' exposure in Mississippi and Vancouver, all the material in the UV protectant test was rated 7 or higher on a 0 to 10 scale. There were early indications of deterioration for the controls with Inert B (no UV protectants), for 2.5% HALS and for 7.5% HALS. Most of the downgrading was due to black stain fungi, suggesting that the biocide combination and concentration used in this part of the test was still inadequate to provide long-term protection. In the biocides test there was a substantial beneficial effect on black stain resistance of additional coats of step one. It was clearly beneficial to have some pre-treatment and it was also clearly important to include the biocides in the coating and not just in the pre-treatment. There were early indications of a positive effect from the incorporation of ZnO with the organic biocides. There was no consistent pattern to allow the effects of Inerts A and B to be distinguished.