New/Untreated: Some new/untreated wood could possibly have a glossy sheen to it. This is “mill glaze,” and it occurs in the course of lumber production. So that you can reach highest adhesion of stain for the wood, the glaze must be “damaged.” One more point to be aware of is http://bookmarkloves.com/story7522834/the-5-second-trick-for-can-deck-paint-go-over-stain