Painting Redwood Lumber

Selection

• Many architects and builders prefer clear redwood because it has a consistent grain that’s free of knots and it readily accepts undercoat and paint. Clear redwood is more expensive than construction-grade redwood, but requires less maintenance for an attractive painted finish. The density of redwood knots is resistant to adequate penetration of paint. For this reason, select construction-grade redwood that has small knots instead of large knots.

Preparation

• The best painting jobs are the result of conscientious practices. Redwood trim, lattice, fencing and siding are installed with rust-resistant galvanized nails or screws. The fasteners should be countersunk, and each countersink filled with wood putty that’s sanded flush for a uniform surface finish. Sanding the exposed surfaces of redwood with medium-grit sandpaper opens the surface grain and makes it more receptive to undercoat.

Undercoat

• Undercoat ensures the finish paint fully bonds when applied and prevents the chemicals that darken redwood from bleeding through. An acrylic or oil-based wood primer can be applied to the exposed surfaces with a paintbrush or sprayer. In harsh climates that endure heavy rainfall, snow and hot sun, apply a second coat of primer for the best long-term results.

Painting

• It’s important that the type of paint used is compatible with the undercoat primer. Always use an acrylic paint with acrylic primer and oil-based paint with oil-based primer. Acrylic paint is applied with a brush or sprayer, and many manufacturers do not recommend thinning. Heavier oil-based paint must be reduced with paint thinner before it can be effectively brushed or sprayed. When using a brush, start at one end of a piece and lightly feather, or blend, the paint toward the starting point as you go. This ensures a consistent finish that’s free of brush marks and paint buildup.