Can I run pressure-treated boards through my planer?
My deck, made of pressure-treated pine, is beginning to look weathered. Is it safe to remove the boards and "freshen them up" by running them through the planer?
—Brent Cale, Jefferson City, Mo.
Aside from the blade-dulling grime unavoidable in deck wood, there are a couple reasons to avoid power-planing pressure-treated (PT) lumber, Brent. PT lumber produced prior to 2003 was treated with Chromated Copper Arsenate (CCA), a preservative containing arsenic. Safety gear, such as gloves, respirators, and proper dust collection, protects you during normal handling. However, the debris created when planing increases your exposure and the chances of introducing the arsenic into the environment.
More recent PT lumber is infused with Alkaline Copper Quaternary (ACQ), which contains no harmful arsenic. However, ACQ has a higher copper content that speeds rust in any ferrous metal it touches—not the type of shavings you want inside your expensive machinery.
For a quicker, easier solution, try removing the deck boards and simply flipping them over. The less-exposed bottom face will not have weathered as much, and a light power-washing will have them looking brand new.