ACQ (Alkaline Copper Quaternary)

ACQ, or Alkaline Copper Quaternary, is a type of wood preservative used to protect lumber from decay and insect damage. It combines copper, which fights fungi and insects, with quaternary ammonium compounds (quats) that enhance its effectiveness. The “alkaline” part refers to the pH environment, helping stabilize the chemicals. ACQ-treated wood is commonly used in outdoor construction like decks and fences because it resists rotting and pests, extending the lifespan of the wood. It is considered a safer and more environmentally friendly alternative to older preservatives containing arsenic or chromium.