Consumer Safety Information Sheet


Alkaline Copper Quaternary (ACQ)

The active ingredient in ACQ is copper, which has long been established as an effective biocide in timber preservation. Quat acts as the co-biocide in the ACQ preservative, providing additional protection from fungi and insect attack that copper alone would not control. Quats are commonly used in household and industrial disinfectants and cleaners and are biodegradable in soil. Copper and quat solutions similar to ACQ are used for the control of fungi and bacteria in swimming pools and spas.

ACQ preservatives penetrate into and remain in pressure-treated wood for a long time. However, some preservative may migrate from the preserved wood into surrounding soil over time and there may be incidental contact with skin during construction or use.

Follow the safe practices listed below when working with pressure-treated wood. Specific work practices may vary depending on the environment and safety requirements of individual jobs.


Wood pressure-treated with ACQ preservatives may be used inside residences as long as all sawdust and construction debris are cleaned up and disposed of after construction.

Do not use treated wood under circumstances where the preservative may become a component of food or animal feed. Examples of such sites would be structures or containers for storing silage or food.

Do not use treated wood for cutting boards or countertops.

Only use treated wood that's visibly clean and free from surface residue for patios, decks and walkways.

Do not use treated wood for construction of those portions of beehives that may come in contact with honey.

Do not use treated wood where it may come in direct or indirect contact with public drinking water, except for uses involving incidental contact such as docks and bridges.

Do not use treated wood for mulch.


Wear gloves to protect against splinters.

Wear a dust mask when machining any wood to reduce the inhalation of wood dusts. Avoid frequent or prolonged inhalation of sawdust from treated wood. Machining operations should be performed outdoors whenever possible to avoid indoor accumulations of airborne sawdust.

Wear appropriate eye protection to reduce the potential for eye injury from wood particles and flying debris during machining.

Wash exposed areas thoroughly with mild soap and water after working with treated wood.

If preservative or sawdust accumulates on clothes, launder before reuse. Wash work clothes separately from other household clothing.

Installation and Maintenance

All cuts and holes that expose untreated wood should be liberally brush coated with an endcut preservative before wood is installed.

For best results, hot dipped galvanized or stainless steel fasteners and fittings are recommended. Direct contact of ACQ treated wood with aluminum is not recommended.

ACQ treated lumber can be painted or stained with any high quality oil or latex based paint or stain. Water repellent coatings can be applied to improve the weathering performance. It is important to ensure the wood is dry and free from surface deposits prior to applying any coating. Always use products in accordance with manufacturers instructions.


Do not burn treated wood. Preserved wood should not be burned in open fires, stoves or fireplaces.

Residential users may dispose of treated wood scraps and cut offs by ordinary trash collection or burial. Commercial and industrial users of treated wood should dispose of ACQ treated wood scraps and cut offs in accordance with local, provincial and federal regulations.