I had some steps built last fall from treated wood, green in color, and this spring I want to soak them down in preservative to make sure they last a long time. My first inclination is copper naphthenate, which is probably the same stuff the lumber was originally treated with. My experience with store bought green copper has not been positive, however. Some posts I covered with it recently were washed off and bare by the end of the season. Seems to me the classic green copper stuff used to work better back in the day. Any suggestions on what I should paint the steps with to preserve them? Maybe a "full strength" green copper preservative is still available somewhere?