If you're building a deck or a similar outdoor project that is at risk of termite infestation, you can protect the wood using a preventative borate treatment. Borate is a water-soluble chemical used to prevent and control termite infestations. The chemical diffuses into wood, creating a barrier through which termites cannot pass. Termites are poisoned when they eat the treated wood. Once treated, the wood must be coated with a finish to seal in the borate.
Clean the wood of dirt and any surface finish, such as varnish. The wood should be dry, with an internal temperature of at least 40 degrees Fahrenheit. If the wood has been stored in a cold environment, place it in a warm location for a few hours before treating.
Cover your work space with newspaper. Ventilate the space by opening a window and running a fan. Wear work gloves, filtration mask and safety goggles to protect your skin, eyes and lungs.
Mix one pound of borate preservative with one gallon of water -- or a multiple of this ratio -- in a bucket using a paint stirrer. One quart of preservative is typically equal to one pound.
Apply the preservative to the wood using a paintbrush. One mixed gallon will cover 150 to 200 square feet of wood. Apply the preservative liberally, thoroughly soaking both ends. Set the wood aside to dry. Wait at least four hours before applying a second coat.
Apply a water-repellent finish to the wood, using a paintbrush, 48 hours after the second coat.
Clean your hands, clothing, paintbrushes and work area using soap and water.