The Guide - Surface Types
Drywall (Sheet-rock)
Drywall is made of gypsum that is covered with paper and used
mostly for interior wall and ceiling construction in residential
and commercial buildings. Very porous drywall can lead to peeling
if low quality primers and paints are used. Assuming the homeowner
has made all the proper surface repairs, new drywall should be
primed with a top quality acrylic latex primer-sealer. This will
provide a good surface for the application of the new paint and
allow a uniform and even finish. Drywall that is being repainted
can be painted with a top quality acrylic latex primer/finish
paint combination.
Hardboard Siding
Hardboard siding is primarily made from wood chips, cooked with
pressurized steam, and refined into fibers. Resins are added to
glue together the fibers and provide strength, and wax is added at
pressing to repel water. Although hardboard siding is factory
primed, it is highly recommended that new hardboard siding be
primed with one coat of a top quality alkyd primer and finished
with two coats of a top quality finish paint. Any cut or exposed
area’s showing through the factory based primer should be spot
primed during surface preparation.
Masonry
New masonry is high in alkaline content and can include surfaces
like brick, concrete, block, stucco, cement, and plaster. Testing
the pH content of the mortar, and the masonry, will indicate if
the masonry has cured enough and is ready for painting. The pH
content needs to be below 9 before masonry is ready to be primed
or painted. Always check with a local paint dealer or contractor
when considering painting masonry. A salty looking substance that
develops on weathered masonry, caused by moisture, should be
scraped off or removed with a wire brush. It is important to use a
top quality primer and paint, that is alkaline resistant, when
priming new masonry to avoid peeling. Preparation, allowing the
proper curing time, and selecting the proper primers and paints
will insure a longer lasting and durable paint life.
Metals
Metals surfaces include iron, aluminum, galvanized iron and steel,
and wrought iron. New metals can contain surface oils if they have
not had adequate time to weather. If at all possible, let new
metals weather for a minimum of six months. If there is no time to
allow for weathering, clean with a solvent to remove oil
treatments that might be present. Painting over oil treatments
will cause adhesion problems. These surface oils can react with
paint and cause peeling. Watch for surface oxidation. Surface
oxidation can be cleaned with steel wool. Any rust that appears on
metals can be scraped down to bare metal, or treated with a
hardening chemical. Properly prepared metal surfaces should be
primed with two coats of either a top quality breathable rust
inhibited alkyd primer, or top quality acrylic latex rust
inhibited primer, and finished with one coat of a top quality
acrylic latex finish paint.
Natural Wood Siding and Decks
Exposure to weathering conditions, mainly water and the
ultraviolet rays of the sun, for two months or more causes wood
surfaces to change. The colours of new wood can begin to turn
yellow or brown, and then to a silver gray. Simultaneously, the
surfaces will develop cracks, the wood grain rises, warping
occurs, and nails begin to loosen. Whenever discolouration appears,
clean the surface with a deck brightener based in sodium
percarbonate, and a pressure washer. Let the surface dry for about
two weeks, and apply a coat of a top quality water repellent stain
or preservative. However, if the weathered look is desired along
with the protection, a bleaching oil, bleaching stain, or
weathering stain is recommended. Top quality water repellent
stains and preservatives are essential for repelling water and
resisting weathering, and are most affective when the wood is
dipped into them, or the stain is applied with a brush. Homeowners
should always be careful of overstaining. Overstaining will cause
the finish to build up. It produces a film on the wood surface
that will eventually peel, blister or crack, and become waxy and
slick. Usually, one coat is all that is needed. If a second coat
is required, make sure the first coat has soaked in good, and wipe
away any buildup or puddles when applying the second coat. All
purpose water repellents and sealers are designed more for
masonry, and should never be used on wood surfaces.
New Wood
It is highly recommended that new wood be primed and painted
immediately. New preservative treated wood can not be painted
without proper aging, because the preservatives will react with
paints and cause wide spread peeling. Preservative treated wood
can be stained with specially formulated preservative treated wood
stain. Paints should be applied when the wood is dry. Woods like
redwood and cedar are prone to "tannin bleeding." Tannin bleeding
is the result of natural dyes that extract themselves from the
woods. These dyes are water soluble and will lead to discolouration
of latex primers and paints. Top quality alkyd based primers work
extremely well in preventing this type of bleeding and should be
finished with a top quality acrylic latex finish paint.
Vinyl Siding
Vinyl expands and contracts with the changing weather conditions,
and normally contains a very slick surface. Good adhesion is
essential for the smooth and slick surfaces that vinyl siding
provides. Never sand, scrape, or cause any other abrasions to a
vinyl surface. Never paint vinyl darker than the original colour
because dark colours absorb heat and could cause the vinyl to warp.
Top quality acrylic latex paints can be applied to vinyl surfaces
once they have been properly washed of debris.
Wallpaper
It is not recommended to paint over wallpaper. Painting over
wallpaper can cause the surface to form large blisters that may or
may not recede, which can cause major surface preparation
problems. Wallpaper should be removed with a wallpaper stripper,
or vinegar, that has been mixed with very hot water. The wallpaper
that is to be removed should be soaked with the solution of choice
so the paste under the paper will breakdown, allowing the
wallpaper to be removed. Wallpaper steamers are also good for
removing wallpaper. Once the wallpaper is removed, the surface
needs to be cleaned of any excess paste, repaired where
applicable, lightly sanded, and primed with a top quality alkyd
stain blocking primer. The priming is necessary to seal any paste
that may have gone undetected. Any undetected paste that is
painted over will react with the paint and cause it to crack.
Homeowners considering a wallpaper project should always prime or
apply a good coat of sizing to the surface before applying
wallpaper. This will allow for easy removal of the wallpaper in
the future. If the surface is not properly prepared before
wallpaper is applied, future removal of the wallpaper and surface
repairs will be extensive.
Paneling
When painting paneling, you first need make sure the surface is
cleaned and free of dirt, dust, etc. Then score the surface with
sand paper, a sanding block, or steel wool. Caulking and filling
cracks is optional. Once all of the surface preparation is
complete, apply one good coat of a stain blocking primer to
prevent the paneling from bleeding through the finish paint. When
the primer is dry, apply two coats of your selected finish paint.
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