Application Techniques for Siding and Trim
The application of a ﬁnish on Western Red Cedar is as important for durability and optimal performance as is the ﬁnish-substrate combination chosen for the job. Finishes can be brushed, rolled, sprayed or applied by dipping. The application technique, the quality and quantity of ﬁnish applied, the surface condition of the substrate, and the weather conditions at the time of application can substantially inﬂuence the life expectancy of the ﬁnish. The application guidelines suggested here should be followed in combination with the manufacturer’s preparation and application recommendations for the product.
Finishes and cleaners are chemicals which may pose health hazards from contact, ingestion or by inhaling. So be sure to carefully read the all of the manufacturers’ application instructions and warnings prior to purchasing the product.
Paints and Solid Color Stains
After completing the surface preparation described above, follow these steps to achieve maximum paint life:
- Apply a good quality stain-blocking primer at the spread rates recommended by the manufacturer as soon as possible after surface preparation and when the moisture content of the wood is below 20%. The primer coat is very important because it forms a base for all succeeding paint coats and should be used whether the top coat is oil-based or latex-based. It is best to prime before installing siding because it permits application to the face, back, edges and ends. Priming the back or wall side of the siding is often referred to as “back priming”. This practice helps to prevent cupping and enhances the paint’s service life.
- Apply the top coat over the primer. Brushing is considered to be the most effective way to apply the coating. If two top coats are to be applied, allow the ﬁrst to cure for the period recommended by the manufacturer before applying the second coat. In cold or damp weather, allow extra drying time between coats.
Solid Color Stains
These may be applied to Western Red Cedar by brush, roller, or pad. Brush application is usually the best. These stains perform similarly and are applied like paint. One coat of solid-color stain is only marginally adequate on new wood. A prime coat with a top coat will always provide better protection to the wood as well as promoting a longer service. Optimal performance can be obtained if the wood is primed, then given two coats of stain. Top coats of acrylic latex solid-color stains are generally superior to all others, especially when two coats are applied over a primer.
Unlike paint, a solid-color stain may leave lap marks. To prevent lap marks, follow the procedures suggested for semi-transparent penetrating stains.
You have the option to apply semi-transparent stains by brush, spray, pad, or roller. Brushing will usually give the best penetration and performance. Spray or roller application followed by back-brushing is also an acceptable method of application. Oil-based stains are generally thin and runny, so application can be messy. Lap marks can be prevented by staining continuous lengths. This method prevents the front edge of the stained area from drying before a logical stopping place is reached. Working in the shade is desirable because the drying rate is slower. Stain that has been applied by spray, without back-brushing, is prone to show blotchy patterns as it weathers.
Two coats of penetrating oil-based stain on textured Western Red Cedar will provide a longer service life than one coat, but only if the wood will accept the second coat. Stir the stain thoroughly during application to prevent settling and color change. Avoid mixing different brands or batches of stain.
Latex semi-transparent stains do not penetrate the wood surface, but they are easy to apply and less likely to form lap marks. These stains are ﬁlm-forming and may not be as durable as oil-based stains.