Does Stain Help Protect Exterior Wood?

Stain Basics

• Stain changes both the appearance and properties of wood. Dye-based stains enter the cell walls and fibers of the wood, creating a deeper color and more durable finish while pigment-based stains bind to the surface of the wood, creating a layer that can contain protective ingredients such as oils, acrylics or polyurethanes.

Exterior Stains

• Stains that will be used on woods that are exposed to the elements need to impart weather and humidity resistance to the wood, as well as water repellent and a seal against fungi and pests, which can destroy the wood. Exterior stains should also be tolerant of a wide continuum of temperatures. Two main types of exterior wood stains are used: wood preservatives and water repellents. These stains can be used separately or in conjunction, and some brands of stain contain a mixture of both types.

Wood Preservatives

• Wood preservatives contain pesticides and anti-fungal properties that kill or prevent infestation by insects or fungi that can eat away or weaken outside woods. Preservatives are classified as pesticides, and, as such, should be used and dispensed of using the utmost care and caution, strictly following the instructions printed on the label.

Water Repellants

• Water repellent stains both penetrate the wood, providing color, and leave an oil- or wax-based layer on the surface of the wood. This layer prevents the wood from soaking in water and reduces the wood’s natural tendency to weather, crack or warp as it dries out or reacts to very cold or very warm temperatures. Water repellent stains can also be applied to wood that will be painted as a protection against decay and rot.