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Historic Preservation - Technical Procedures
Applying A Semi-Transparent Or Opaque Stain To Wood
Developed For Hspg (Nps - Sero)
Wood And Plastics
Applying A Semi-Transparent Or Opaque Stain To Wood
APPLYING A SEMI-TRANSPARENT OR OPAQUE STAIN TO WOOD
A. This procedure includes guidance on applying a semi-
transparent or opaque stain to wood surfaces. This
coating will prolong the service life of wood and provide
some protection against agents of deteri= oration.
NOTE: IF THE WOOD WAS ORIGINALLY FINISHED WITH A FULL
BODY PAINT, IT SHOULD BE REPAINTED RATHER THAN STAINED,
AS THE VISUAL APPEARANCE OF STAIN IS NOT COMPATIBLE WITH
THAT OF PAINT. SOME STAINS, HOWEVE= R, MAY BE SUITABLE
REPLACEMENTS FOR WHITEWASH PAINT. = CONSULT THE RHPO FOR
GUIDANCE AND RECOMMENDATIONS.
B. Natural causes of wood deterioration include decay= ,
ultraviolet degradation, insect infestat= ion and excess
C. Some types of problems resulting from the weatheri= ng
1. Fungi and/or mildew growth
2. Warped boards
3. Loose fasteners
4. Changes in surface texture resulting in cracks and
D. In addition to opaque paints, various so-called "natural"
finishes and colored stains provide this necessary
protection. And, like paints, proper surface preparation
and application are vital to long lasting protection.
E. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precaution= s
4. Quality Assurance
5. Delivery, Storage and Handling=
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
A. Semi-transparent Penetrating Stains: Thin, moderately
pigmented water repellents and water repellent
preservatives which penetrate the wood allowing the
natural grain and texture to show throug= h.
1. The addition of the pigment protects the wood
against ultraviolet degra= dation and increases the
durability of the finish.=
2. Semi-transparent penetrating stains made from water
repellent preservatives (WRP's) are recommended:
a. They provide additional protection against
b. They penetrate the wood rather than forming a
film they will not peel, flake or blister.
B. Solid Color (Opaque) Stains: Provide an opaque finish
with a slightly lower concentration of pigment than
regular paints. They result in a flat finish which hides
the natural color and grain of the wood but maintain the
original texture. Available in both an oil-based or
latex-based product, solid color stains form a thin film
on the surface of the wood and are there= fore subject to
peeling, flaking, etc., just as paint is.
1.03 DELIVERY, STORAGE AND HANDLING
A. Storage and Protection: Stains shall be in sealed
containers that legibly show the designa= ted name, formula
or specification number, batch number, color, quantity,
date of manufacture, manufacturer's formulation number,
manufacturer's directions including any warnings and
special precautions and name of manufact= urer. Stains
shall be stored on the project site and shall be stored
to prevent freezing. They shall be kept covered and
safeguards taken to prevent fire.
1.04 PROJECT/SITE CONDITIONS
A. Environmental Requirements:
1. Unless otherwise recommended by the manufacturer,
the ambient temperature shall be between 50 degrees
F. and 95 degrees F. when applying either a stain
2. Do not apply when the relative humidity exceeds 85%
or the moisture content of the wood exceeds 12% as
measured by an electronic moisture meter.
3. Do not apply a stain in the direct sun. They shall
be applied only when the surface to be treated is
in the shade and the sun is shining on the opposite
elevation. The west elevation should be treated in
the morning when the sun is shining on the east
elevation; the north elevation should be treated
around noon when the sun is shining on the south
elevation; the east eleva= tion should be treated in
the afternoon when the sun is shining on the west
elevation; and the south elevation should be
treated late in the after= noon when it is in full
4. Do not apply stains to damp surfaces, in misty or
rainy weather, in the snow or where there is
visible ice or frost on the surfaces.
5. For optimal results when using a latex stain do not
apply when the temperature is expected to go below
50=F8 F. within 24 hours of application. On hot, dry
days, to prevent the stain from drying too quickly,
the surface can be slight= ly dampened before the
application of a latex stain. Be sure to follow
all manufacturer's instru= ctions.
A. Semi-transparent Penetrating Oil-based Stains Finish:
1. The life expectancy of these stains varies
tremendously depending on whether one coat or two
coats of stain were appli= ed initially.
a. A single coat, applied to smooth wood should
last 2 to 4 years.
b. A two coat system, however, should last up to
8 years depending on the exposure. Coastal
expos= ures or cold environments especially at
high altitudes will deteriorate more quickly,
as will most southern exposures. A loss of
color is a good indication that the finish
must be renewed.
2. Clean surfaces with a stiff, nonferrous bristle
brush to remove dirt and loose wood fibers.
3. If the surface has mildewed, wash with bleach and
detergent, rinse and let dry completely before
applying a new coat of stain.
NOTE: Because of the more porous nature of weathered
wood and the better penetration of stain that results,
subsequent applications will last somewh= at longer than
the initial application.
A. The Sherwin-Williams Co.
101 Prospect Ave. NW
Cleveland, OH 44101
B. Olympic Stain
2233 112th Avenue, NE
Bellevue, WA 98004
800/426-6306 or 206/453-1700
C. Samuel Cabot, Inc.
100 Hale Street
Newburyport, MA 01950
D. Rez Finishes (Division of PPG)
One Gateway Center
Pittsburgh, PA 15222
800/441-9695 or 412/434-3131
E. Minwax Co., Inc.
16 Cherry Street
Clifton, NJ 07014
F. Benjamin Moore
51 Chestnut Ridge Road
Montvale, NJ 07645
G. Flood Company
PO Box 399
Hudson, OH 44236
1. Conventional spar, urethane and marine varnishes
are generally not recomme= nded for exterior use.
These film forming finish= es are quickly degraded by
sunlight. If a long service life is not required,
and the area to be varnis= hed is fully protected
from the sun, varnishes can be used satisfactorily
if properly applied, See Part 3 - Execution.
2. All stains shall be from the same manufacturer to
avoid problems with penet= ration and coverage.
Different batches of stain, even from the same
manufacturer, should also be avoided for the same
B. Oil modified alkyd semi-transparent penetrating stain
such as "S-T Wood Preservative Stain, A14T5" (Sherwin
Williams), or approved equal. Other manufacturers are
listed in Section 2.01 above.
1. Oil/alkyd based semi-transpare= nt penetrating
stains, which contain a wood preservative, are
recommended over latex-ba= sed products. Latex-based
stains do not penetrate the surface and are subject
to peeling, flaking, etc.
2. These stains are most effective on rough lumber and
plywood, smooth lumber, weathered wood, and flat-
grained surfaces of dense species that do not hold
3. They can also be used over other penetrating
finishes which have weath= ered to the point of
needing to be renewed.
4. They are NOT, however, effecti= ve over paint, solid-
color (opaque) stains or varnish, nor on smooth
Solid color (opaque) stain such as "= ;Series A14" (Sherwin
Williams), or approved equal. Other manufacturers are
listed in Section 2.01 above.
1. Though both oil- and acrylic-b= ased solid colored
stains are available, the acrylic-based stains are
considered by the USDA's Forest Products Laboratory
to be the best of the opaque stains and are
2. If the choice has been made to use an opaque stain,
their use is recommended when going from a
semitransparent penetrati= ng stain or an opaque oil
stain to a lighter color, to cover a previously
creosoted surface, or when covering new, close-
pored wood species such as Southern yellow pine.
Like latex paint, acrylic= -based opaque stains are
also more resistant to mildew, are easy to apply
and clean-up with soap and water.
3. Oil-base opaque stains may be successfully used on
fresh, clean wood but they are NOT recommended for
previously painted wood, even if all of the paint
has been removed. N= or are they recommended for
reapplication over existi= ng oil-based opaque
stains. In both cases an uneven, splotchy
appearance can be the result.
4. Solid color stains, either oil- or latex-based, are
NOT recommended for flat, horizontal surfaces such
as window sills, handrail= s, porch floors, or decks.
C. Raw linseed oil: The linseed oil shall be clean and
colorless so that it will not adversely affect the
texture or durability of the paint.
D. Caulking compound:
1. Polyurethanes - easily workabl= e; paintable; 15-20
year life span; limited availability, see section
on products and suppliers= .
2. Polysulfides - slow drying; can be sanded and
painted; highly elastic; limited availability, see
section on products and suppliers.
3. Butyls - paintable but cannot be sanded; 7-10 year
4. Silicones - some can be painted but generally not
5. Acrylic Latex - for exterior work, their use is
best left to tight, narrow joints; short life span
especially when compared to polysulfides and
1. Use natural bristle paint brushes for oil/alkyd
stains. Precondition by soaking in raw linseed oil
for 24 hours. Use nylon bristle brushes for latex
stains. Do not use the same brush for both types
2. For thin, runny stains, foam pad applicators can be
3. Stiff natural bristle scrub brushes.
A. Surface Preparation: Like any paint system, the surface
to be treated must be clean and free of any loose, rough
wood fibers, loose paint or varnish , or any mildew,
grease or dust. The surface must be as meticulously
prepared for a stain as it would be if it were being
painted. See 06300-02-R for guidan= ce on preparing wood
surfaces for recoating.
3.02 ERECTION, INSTALLATION, APPLICATION
A. Mixing the Stain:
1. Mix the stain thoroughly and frequently. This is
important in maintaining an even color coverage.
2. Pour off the top oils to a smaller container. Stir
the remaining contents until well mixed, add back
the top oils and mix thoroughly again. If
possible, do all of the mixing in a larger
container, i.e. use a five gallon paint to mix 2-3
gallons of stain. T= his will allow more vigorous
and thorough mixing witho= ut fear of spilling.
3. When the first batch of stain is about 2/3 gone,
stir the remaining stain into a new batch of stain.
This will help even out any differences in color
and pigment concentrations between cans.
4. Throughout the application stir the stain often to
keep the pigments and oils well mixed.
B. Applying a semi-transparent (oil-based) penetratin= g
NOTE: The application of a semi-tr= ansparent penetrating
stain is best performed with a brush as it provides the
best control. Stains may also be spray- or roll-applied;
however, an even application is difficult to achieve
using either of these methods. For stains that are
especially thin, foam applicators will help control the
1. For dense species of wood such as Douglas Fir or
Southern pine, treat the surfaces first with a
water repellant preservat= ive and let the wood
weather for a year before staining. See 06310-01-P
for guidance. This will allow the first coat of
stain to penetrate more deeply and uniformly
because the surface is more porous and will result
in a more durable finish.=
2. Start at the top of the area to be stained and work
down, applying the stain to a small number of
boards or a single panel at a time. This will help
avoid lap marks. If possible, stop at a logical
breaking point such as the end of an individual
clapboard or at a door or window.
NOTE: DO NOT LET THE FRONT EDGE DRY BEFORE
BEGINNING THE NEXT SECTIO= N.
a. When using a commercially available stain,
follow all manufacturer's instructions.
b. When using semi-transparent oil-based
penet= rating stains, one gallon will cover
appro= ximately 200-400 SF when applied to a
smooth surface, and 100-200 SF when applied to
a rough or weathered surface.
3. For rough or weathered surface= s, apply two (2)
successive coats of the stain.
a. Brush on the first coat of stain, again
worki= ng in small, logical areas. Allow each
coat to soak into the wood for 20 to 60
minut= es before applying the second coat, but
do not allow the first to dry completely.
b. About an hour after the application of the
second coat of stain wipe off any excess stain
with a cloth, sponge, or brush which has been
sligh= tly dampened with the stain.
4. When used to cover an old, weathered penetrating
a. Brush with a stiff bristle brush to remove
dust and loose wood fibers.
NOTE: DO NOT USE FERROUS BRUSHES OR WOOLS.
THESE CAN LEAVE SMALL IRON PARTICLES ON THE
SURFA= CE OF THE WOOD. CERTAIN WATER-SOLUBLE
EXTRA= CTIVES NATURALLY FOUND IN SOME WOODS SUCH
AS WESTERN RED CEDAR, REDWOOD, DOUGLAS-FIR AND
OAK CAN REACT WITH THE IRON PARTICLES CAUSING
BLUE-= BLACK STAINING.
PENTA= CHLOROPHENOL, A COMMON WOOD PRESERVATIVE
OFTEN FOUND IN SOME WRP'S AND SEMI-TRANSPARENT
PENET= RATING STAINS, CAN ALSO CAUSE LOOSE IRON
PARTI= CLES TO CORRODE WHICH CAN IN TURN REACT
WITH THESE SAME WATER-SOLUBLE EXTRACTIVES
CAUSI= NG THE SAME BLUE-BLACK STAINING.
b. After applying the new coat of stain carefully
exami= ne the surface.
1) A dull, flat surface will indicate that
the stain has evenly penetrated the wood.
2) A slightly glossy surface will indicate
that penetration of the stain was uneven
resulting in a less durable surface which
will need to be renewed more often.
5. During application, if it is possible, remove any
trim pieces which are to be stained a different
color because it is diffi= cult to cut-in stain. For
better control and more even coverage and
penetration, prestain any new wood.
C. Applying a solid color (opaque) stain:
NOTE: Opaque stains react much the same way as do oil-
based and latex paints. Brush application is the best
but a roller may also be used. Fol= low the same
procedures outlined for semi-transparent penetrating
stains in Section 3.02 B. above.
A. As with quality surface preparation for painted surfaces,
caulking joints is an important part of surface
preparation. CAULKS, however, ARE NOT STAINABLE, so
caulk after staining has been complete. Also caulk after
a WR or WRP has been applied.
END OF SECTION