Stains perform well on many types of wood with unusual characteristics, including knots, texture and siding that's exposed to severe weather conditions. Most stains contain water repellents and in many cases rot and mildew inhibitors. Transparent stains contain no pigments but have water-repellent features that protect the wood without hiding the natural coloration, and slow the natural color change process. They modify the original wood color and to a lesser degree the characteristics of the wood, such as grain and knots-but not enough to take away from the overall impact of the wood's natural qualities. Semi-transparent stains are much more durable than transparent stains.
Opaque stains are high in pigment content and thoroughly hide the grain and color of the wood.
The surface texture is retained, but these opaque stains tend to perform like paint, and do not penetrate the wood so deeply. All stains should be applied over clean, dry surfaces so, for best results, use a stiff bristle brush to remove any surface dirt, dust and loose fibers. For a uniform covering, mix the stain thoroughly before and during applications. Brush stain continuously in patches of workable proportions, always leaving a wet edge to prevent lap marks. For vertical siding, begin at the top of several boards and continue all the way to the bottom.