A deck is an extension of your home, much like an outdoor living room. Of course, you want the wood to look smooth, lustrous and evenly stained.
But several factors can detract from its beauty, dulling the finish and allowing mold to grow:
Age
Moisture
Sun
Pollen
Weather and climate
Many homeowners try to refinish their decks themselves only to have to strip and stain year after year. Inferior results are usually the result of use of the wrong products or tools.