If wood is not protected from environmental hazards it blackens, becomes slippery the risks of moulds forming in its layers and being inhabited by parasites increases. These harmful effects will eventually destruct the wood, it will become unstable and product loses its appeal. We recommend you to clean the wood first, using appropriate detergents that will help to remove dirt and eliminate pests. You will be able to enjoy your wooden, terrace for instance, for a long time after taking adequate protection measures.