Unfinished hard Adirondacks will typically change a soft silvery gray. You will desire to sand these Adirondacks once a year, ever-so marginally, with or 150 grit sand-paper. That is only for the purpose of "knocking down" any irregular bleary feed that might naturally occur as an effect of exposure to the the weather. It will remove any larger fibers that separate away and could cause splinters. In addition, it provides an appearance that is sleek and even to the Adirondack furniture. Don't sand through the silver to show the normal shade of the timber. The purpose just isn't to take away the silver aging but to merely maintain it easy and looking grand!