Finishing Concepts
Western Red Cedar is a versatile and practical product for finishing, both
indoors and out. A wide range of effects are possible with the various stains,
bleaches and paints this wood accepts so well-largely due to its freedom from
pitch, dimensional stability and fine grain-characteristics which help ensure a
minimum of maintenance and long lasting results.
Built-in resistance to decay gives Western Red Cedar a durability that is
extended even further by careful application of stains or paints. They enhance
longer wood life and provide a maintainable surface in the color tone desired.
The wood's dimensional stability helps to prevent paint cracking caused by
shrinkage and swelling of the siding, thus extending the finish life.
Finishing Western Red Cedar is easy if one starts with the right materials.
For best results, purchase the better grades of finishes and select the best
tools. Quality finishes may cost more initially, but their longer service life
makes them more economical in the long run.
A Guide to Exterior Finishing
While Western Red Cedar can be left unfinished to a soft silver grey
(dependent on weather and exposure conditions), finishes are recommended to
provide a uniform, cleanable surface, or perhaps to modify it to a preferred
color tone for architectural purposes.
Western Red Cedar is a natural for all exterior finishes. Its built-in
resistance to decay and dimensional stability ensure years of trouble-free
service and lasting good looks.
When selecting and applying a finish for use on surfaces exposed to adverse
moisture conditions, use a finish with a fungicidal additive which will
eliminate or reduce discoloration caused by mildew growth.
Stains
Most people are attracted to exterior wood finishes that help retain as
"natural" an appearance as possible. More and more semi-transparent
finishes on the market have approached this ideal and most also include bonus
ingredients of water-repellency additives and mildew inhibitors.
There are two types of natural wood finishes: film-forming and penetrating.
Film-forming finishes such as varnishes and urethanes do not penetrate the wood
and are to be avoided for exterior application. They lack the permanence needed
to extend the life of the wood, and must be refinished again in a year or two.
Because film-forming finishes do not penetrate the wood, they prevent the
release of moisture within the wood, which results in cracks and blisters.
Latex Stains
Latex stains do not penetrate the wood surface and tend to perform like thin
paints. They do however have some porosity which allows limited moisture
movement with the wood underneath, providing more stability between the stain
and the substrate. The shorter service life of these non-penetrating finishes
can be improved with the use of a stain resistant primer.
Latex stains are available in a wide range of colors and allow easy cleanup
with water.
Advantages of Penetrating Stains
Natural appearance and protection from moisture are advantages provided by
penetrating stains. Since the stains penetrate the wood, there is no peeling or
blistering as commonly seen in painted exteriors. 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. Penetrating stains come
in three types: transparent, semi-transparent and opaque.
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.
Semi-transparent stains, because of the added pigment, are less
"natural", but equally beautiful. 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.
Application
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.
Stains are best applied by brush for maximum penetration (natural bristle
brushes for oil-based stains, synthetic brushes for water-based stains). 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. For horizontal applications start at one
corner and work to an obvious stop.
For smooth surfaces that are not too absorptive, two coats of stain are not
recommended because the second coat won't penetrate and may result in uneven
glossy spots. On smoothly-planed wood surfaces a one coat application will last
about three years. Rough-sawn and weathered surfaces are much more absorptive
and are finished best with two coats of penetrating stain, which should last
eight to ten years, providing the second coat is applied within one hour of the
first so they both penetrate the surface. Stain that has not penetrated after an
hour should be wiped off, for a uniform look.
Bleaches
A uniform weathered effect can be achieved in several months with special
bleaching agents available from most leading manufacturers-but use this method
on new wood only; it's particularly effective on rough-sawn or saw-textured
cedar. Use a brush and apply one or two coats. A water-repellent or transparent
penetrating stain can be applied in one or two seasons after the bleaching agent
has achieved the desired greying. Note: A similar effect can be simulated with a
grey pigmented stain.
Wood Preservatives
A water-repellent preservative can be the only treatment on the exterior if
you wish to retain the natural look of Western Red Cedar. Two coats are
recommended if this result is desired, however frequent renewal applications may
be required depending on climate and exposure conditions.
Paints
If you plan to paint the exterior, then ideally, a water-repellent
preservative is best applied to the bare wood before the siding is installed.
Butt joints and wood laps should receive special attention as well as other
potential spots where water might seep in. After the water-repellent has
thoroughly dried, the bare wood is primed, again, preferably prior to siding
application. Since the primer is the base for all subsequent painting, it must
be applied carefully. For Western Red Cedar siding, either an oil-based or
alkyd-based primer is best. Some latex based primers are also designed to go
over cedar. Enough primer should be applied to obscure the wood grain.
Two topcoats are applied over the primer. If it is not practical to
double-coat the entire house, then consider two coats on the south and west
sides, because they weather more quickly.
There are three types of paints to choose from: oil, oil alkyd or all-acrylic
latex. All-acrylic latex paints are easy to use and very easy to clean up with
water afterwards, with no potential risk of fire hazard from oily rags,
thinners, etc. Most professionals and do-it yourselfers prefer it. Oil adheres
better, but preparation and cleanup discourages many. Oil alkyd is faster
drying, but presents the same problems as oil.
Painting Exteriors
New Wood: Paint as soon as possible after the siding is installed. Use
non-corrosive fasteners such as hot-dipped galvanized, aluminum or stainless
steel to prevent streaking and ruining the finish. Use a dry brush to remove
dust, particles of wood and other foreign matter before you paint. Seal all
cracks around doors and windows, and wherever wood comes together, with caulking
compound to prevent moisture problems.
To minimize moisture problems, we recommend that fans be installed in
kitchens, bath and laundry rooms. Attics should be ventilated, crawl spaces
covered with 3 or 4 mil polyethylene film and the area properly vented. During
the building stage, it's wise to install vapor barriers behind the inside walls
in those rooms that create the most moisture, to prevent paint blistering and
peeling to the exterior walls.
The novice painter would be well-served to first paint the exterior wall on
the most secluded side of the house. Start with the siding, and paint with the
grain. Don't paint in the direct sunlight. Next paint the inner trim of the
window and move outward. All other trim is done last.
Old Wood: If the exterior walls are severely blistered or peeling, you
may have a serious moisture problem that must be solved. Exhaust fans, attic
louvers or fans, vented holes or wedge vents and caulking may be necessary
before repainting. Alligatoring will require power sanding down to the bare
wood, then priming and painting. Chalking can be removed by washing. Mildew can
be treated with a good wash-down, using household detergent then mixing bleach
with water and letting it sit on the affected area for a few minutes before
rinsing off.
WARNING: Never mix bleach with cleaning solutions
containing ammonia. It's extremely dangerous to your health.
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