The initial application of paint or wood stain is absorbed into the
substrate. Since stains contain low amounts of binder, the pigment
remains near the surface, while the binder penetrates to a deeper
level. On the other hand, paint has a high amount of binder, so the
pigment forms a layer on the surface.
Wood stains range from very
low viscosity to extremely thick. The thicker stains are designed
primarily for exterior use. They penetrate better than paint, but
usually do not hide surface defects as well. Exterior stains tend to
be more flexible than paint and last longer. If you decide to use
stain, be aware that most cannot be painted over. So once a surface
has been stained, that’s most likely how it will have to stay for
life.
Applying wood stain is not usually too difficult. Most are brushed
or rubbed onto the wood. But surface conditions can complicate things.
Highly porous and dry woods will typically absorb the stain quickly -
so fast, that several coats may be needed to reach the desired color
depth. The ends of cut wood will absorb very fast and can cause color
differences between top and sides.
Fast-drying stains can be difficult to apply in hot weather
or direct sunlight. Slow-dry varieties will take a very long time to
dry in cold and/or damp conditions. Be sure to check the labels and
match drying time and temperatures.
Some mills put sealants on the surface of new lumber for added
protection. The problem is, wood stains cannot penetrate these
products. You will have to strip or sand the surface before staining.
For even absorption of stain, sand the surface evenly with
fine-grit paper. Blow off the dust and then apply stain as per
instructions. More coats equals more penetration, but also more
pigment near the surface. This tends to darken the wood and hide some
of the surface.