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Application
How a finish is applied to cedar is as important
for durability and good 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 concert with the manufacturer's directions
for the product.
Paints
Paints of all types such as vinyl-acrylic,
modified-acrylic, and oil-based top coats
are all suitable for cedar but test results
show that good-quality 100%-acrylic formulations
perform best. To achieve maximum paint life,
follow these steps: |
1. On bare new or restored cedar, apply one coat
only of water-repellent preservative (1% or less
of wax by volume and content). Allow it to dry for
the period of time recommended by the manufacturer.
If the wood has been dip treated, a longer drying
time may be needed. Do not paint before the solvent
from the water-repellent preservative has evaporated
because the paint may then be slow to dry, may discolor,
or dry with a rough surface.
2. Apply a good quality stain-blocking primer
as soon as possible after the water-repellent
has dried. 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. Application rates recommended
by the manufacturer should be followed.
3. Apply the top coat over the primer. If two
top coats are to be applied, allow the first to
cure for the period recommended by the manufacturer
before applying the second. In cold or damp weather,
allow extra time between coats.
Water-Repellent Preservatives
Water-repellent preservatives should be used only
on newly manufactured bare cedar, on restored
bare cedar, or on cedar previously treated with
the same type of product. Application of preservative
by brush, pad, or roller followed by thorough
back-brushing is equally effective. When cedar
is treated after the structure has been completed,
liberal amounts of the solution should be applied
to all lap and butt joints, edges and ends of
boards. Other areas vulnerable to moisture penetration,
such as below doors and window frames, also need
to be treated.
When used as a natural finish, the service life
of a water-repellent is only one to two years
depending upon the wood and the exposure. Treatments
on textured surfaces generally last longer than
those on smooth surfaces. Dip treatment prior
to installation or repeated brush treatment to
the point of refusal will enhance the finish durability.
The more finish absorbed by the wood, the longer
the service life. If a water-repellent preservative
is used as a pre-treatment before painting, apply
only a single coat, and use caution to avoid excessive
build-up.
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Semi-Transparent,
Oil-Based Penetrating Stains
Semi-transparent, oil-based penetrating stains
may be applied 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. These 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 particularly prone to show blotchy patterns
as it weathers. |
Two coats of penetrating oil-based stain on textured
cedar will provide 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 are not as durable as oil-based stains.
Solid-Color Stains
Solid-color stains may be applied to cedar by
brush, roller, or pad. Brush application is usually
the best. These stains act much 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 and longer service.
The best performance can be obtained if the wood
is primed, then given two coats of stain. Top
coats of 100% 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.
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