The favorite FPL report, Installation, Care, and Maintenance of Wood Shake and Shingle Siding, discusses semitransparent penetrating oil-based stains. These stains are similar to water-repellant preservatives (WRPs), but have considerably more pigments than WRPs.
As with WRPs, new semitransparent finishes are low in organic solvents and may not penetrate wood as well as traditional semitransparent stains. Semitransparent stain provides a color without entirely concealing the color, grain, and texture of the wood. Stains with the highest pigment concentration will provide the longest service life and provide the most protection from weathering. Some companies formulate stains especially for use on wood shakes and shingles. (Check the internet for “wood shingles and paint” to find leads on paint manufacturers having products for wood shakes and shingles.) Stains that contain a water repellant and wood preservative will provide additional protection and further extend the service life of your siding.
Oil-based stains penetrate the wood and generally give longer service life than latex semitransparent stains do. Oil-based formulations degrade by slow erosion of the pigment from the surface and it is seldom necessary to do extensive surface preparation prior to refinishing. Latex semitransparent stains do not penetrate the wood but form a thin film on the surface. They tend to fail by flaking and may require extensive surface preparation prior to refinishing. Paint manufacturers and resin suppliers are making progress to overcome these limitations.