Types of Pressure Treated Preservative Chemicals

ACQ – Alkaline Copper Quat – Safer compound used to substitute CCA. This compound is highly corrosive to steel. You must use triple galvanized or stainless steel hardware and fasteners when in contact in ACQ treated wood.

AC2

CCA – Chromated Copper Arsenate was once the most widely used compound. On January 1, 2004 the EPA in a voluntary agreement with the industry began to restrict the use of CCA treated lumber. This was an effort to reduce arsenic use and improve environmental safety. CCA treated wood has a very distinct greenish color. This preservative was very effective in demonstrating high levels of retention following pressure treatment, meaning that the chemicals remain well bonded to the wood and are not very prone to leaching effects. CCA is a very toxic and hazardous preservative that must be handled with caution.

Creosote – Leaves an oily residue on wood that won’t accept paint and is also a skin irritant and a fire hazard.

Pentachlorophenol (penta) – This compound is severely toxic to humans, animals, and plants. It is a relatively clear compound that can bloom on the surface of the wood to create hazardous crystals that can leach into the ground.

Copper-8-Quinolinolate – Oil borne preservative that is odorless and relatively safe for people to handle. It is the only wood preservative chemical that is permitted by the FDA to come in contact with food.

Sodium Borate – Used extensively in Australia and New Zealand it has been introduced on a limited basis to the U.S. and Canada. It is sometimes referred to under the brand name Tim-bor wood preservative. It is applied by a dip diffusion method, which relies on open tanks instead of a pressure chamber. It is highly toxic to carpenter ants, termites and other wood boring insects but isn’t toxic to mammals. It doesn’t add a color or odor to the wood. Borate treatment has a limited capacity to prevent mold and fungus so it cannot be used in contact with the ground.