I write in regard to the Science & Technology Concentrate “Deck Stains Seal in Contaminants” (C&EN, July 26, page 34). My son recently did an Eagle Scout Project resealing the tops of posts along the waterfront promenade in Havre de Grace, Md.
The tops of every upright post had been sealed with a coating when the promenade was first constructed 10-plus years ago. Since the tops of the posts exposed the grain of the wood to rain, the ends were coated to prevent the washing out of the chromated copper arsenate wood preservative. Over time the coating had mostly worn off and flaked away. Topping the posts with a metal or plastic cap was ruled out due to liability issues.
No one knew what the original coating was. After much research, my son learned that pile-driving companies had been using asphaltic roof coating for many years on the tops of wood piles since creosote had been banned. Doing more research of whether to use fibrated or nonfibrated asphaltic roof coating, he contacted the technical service department at Gardner-Gibson. They informed him that they had an asphaltic water emulsion paint called Black Beauty that was specifically designed for this exact purpose. It seals the posts; dries to a hard finish, unlike roof coatings; and lasts for many years, unlike penetrating stains.
I am sure that most homeowners don’t want black decks. But for preventing most of the leaching through the grain of upright posts, this is an excellent, long-lasting solution.