CCA News & Information Articles

Effects of deck washes and brighteners on the leaching of CCA components 12-01-2001 There has been concern that bleaching and other agents in commercial deck washes and brighteners could aggressively leach chromated copper arsenate (CCA) components from treated wood. Natural rain water drippage was collected over several rain events from small-scale CCA type C treated southern pine decks and from an approximately 12-year-old CCA-C treated spruce/pine/fir deck installed in New Brunswick, Canada. The decks were then treated with a number of commercial deck washes/brighteners, and the CCA components in the wash solution were compared to those from water wash only and from the natural rain events. Treatments containing phosphoric acid, citric acid, and oxalic acid resulted in relatively high copper losses during the washing treatment and slightly increased losses of the other components. Strong oxidizing agents such as sodium hypochlorite and sodium percarbonate resulted in oxidation of chromium to the hexavalent state and subsequent loss of soluble hexavalent chromium. Alkaline sodium hydroxide and sodium borate treatments also mobilized some hexavalent chromium. Losses were much higher from new decking than from a deck that had been in service for approximately 12 years.