Most sealers will only provide water repellency with limited UV protection. Water sealers will normally let the wood naturally grey out within 3-6 months due to the lack of pigments and UV inhibitors. On the other hand, stains will not only provide water resistance, but also have UV protection, mildew and fade resistance, and have a higher opacity. Because of these facts, stains last up to 5 times longer than sealers and look more professional. However, applying a stain requires special skills. At DeckMaster our technicians are fully trained and use airless spraying equipment to obtain the most uniform finish possible. Unless you like the grey appearance you should never use a clear sealer.