WHY SOME PAINTS FAIL
Understanding the primary causes of paint failure will help you
plan your paint project better. The primary causes of paint failures are moisture,
inadequate surface prep, improper application and weathering.
Be aware however that the majority of paint failures are related to moisture
and/or inadequate surface preparation. You can learn quite a bit more about
this by reading the paint surfaces section. Some
of the more common paint failures are listed below in alphabetical order with
recommendations for their prevention.
Alligatoring is cracked paint which resembles alligator skin, and is generally found on wood surfaces. Alligatoring occurs when paint cannot adhere to a glossy surface, when a second coat of paint is applied over an inadequately dried first coat of paint or from weather aging. It can also occur when applying excessive coats of paint, when the finish coat expands/contracts more than the underlying coats. To remedy alligatoring of paint it must be completely removed so that an even and uniform finish can be painted over. Wood surfaces should be primed with a top quality alkyd primer and acrylic latex finish.
Bleeding refers to surface discoloration commonly found on exterior wood surfaces
and hardwood siding, ceilings, repainted wallpaper, or when light colored paint
is applied over dark colored paint. The causes of bleeding are moisture and
water soluble dyes located within wood surfaces and wallpaper or inadequately
primed surfaces. Bleeding on hardboard siding is caused by wax. The removal
of any excessive water source is essential before any surface preparation can
be completed. This can be overcome by priming the area with top quality alkyd
based primers and finished with top quality acrylic latex paints. Interior surfaces
should be primed with either a top quality alkyd based or acrylic latex based
stain blocking primer, and finished with a top quality acrylic latex finish
paint.
Fresh paint applied in direct sunlight and moisture causes paint to blister.
Surfaces repeatedly heated by the Sun become hot and can prematurely dry new
paint, causing blistering. This is more common with dark or dramatic colors
because they, in addition to surfaces, absorb heat. Heat blistering will have
a layer of paint under the blister if the surface is being repainted. Trapped
moisture in walls or behind surfaces will eventually try to escape through painted
surfaces, also causing blistering. Moisture blistering will reveal a bare surface
under the blister. Blistering surfaces should be scraped and sanded smooth,
primed with a top quality alkyd or acrylic latex primer, and finished with a
top quality acrylic latex finish paint. If moisture blistering occurs on a repainted
surface, spot priming of bare spots will be necessary to ensure a uniform and
even finish before the final priming and painting is completed.
Chalking is the weathered powder found on exterior painted surfaces and is paint's natural normal way to weather away. However, premature chalking can be caused by inadequate priming or thin paint. Homeowners should be aware that chalking on siding located above masonry will run during rainy weather causing the masonry to stain. Once a chalked surfaced is pressured washed clean and prepared for painting, one coat of a top quality alkyd primer and one coat of a top quality acrylic latex finish paint is highly recommended for the prevention of future excess chalking.
Checking is an early form of cracking and occurs when paint begins to loose
elasticity, forming narrow breaks on the painted surface. These breaks later
swell and turn into cracks. Checking and cracking are found on wood surfaces
with multiple layers of paint or plywood. Checked or cracked paint should be
completely removed from surfaces before repainting. Properly prepared wood surfaces
should be primed with a top quality alkyd primer and finished with a top quality
acrylic latex finish paint.
Efflorescence is a white salty substance that forms on masonry and plaster
due to moisture migrating through the surface. If left untreated for long periods
of time, it will become hard and crusty. Any source of excessive moisture must
be eliminated and the surface must be cleaned by scraping or wire brushing.
Surfaces must be repaired before priming and painting. Surfaces can be painted
with top quality alkyd or acrylic latex based primers and paints that are alkaline
resistant.
Fading is caused by the natural weathering due to the ultraviolet rays of the
Sun. Chalking pigment, alkali from masonry and tint intended for interior based
paints but used on exterior surfaces will cause paint to fade prematurely.
Hatbanding is caused by the over cutting in of interior walls, ceilings , and
trim corners, and the use of excessively long roller naps. It occurs when wet
paint is applied over dry paint. Hatbanding is very noticeable with dark and
dramatic interior colors and sheens. Using small nap rollers and applying a
thin brush coat of paint will help eliminate this effect.
Overlapping is due to inadequate paint application and is often seen on exterior
surfaces. Siding should be brush painted one piece at a time horizontally and
from one end to the other without stopping. Otherwise, any paint you apply can
dry too fast and cause overlapping where brush strokes overlap: another good
reason why protective coatings should never be applied in direct sunlight. Coatings
should be applied in shady areas on warm days and should be applied ahead of
the Sun in cooler months. Staying ahead of the Sun will allow the heat to come
around and dry freshly painted areas.
Mildew is a fungus that grows best in a warm humid climate and is often found
in but not limited to shaded areas. Mildew can appear in a variety of colors
and prefers painted surfaces because of the nutrients that paints provide. These
same nutrients float through the air, land on painted surfaces and become food
to mildew. Mildew grows faster on flat surfaces than on glossy surfaces and
is attracted to linseed oil based products that contain no mildewcide. Most
paints and stains come already made with mildewcide included. However, mildewcide
can be added to paints and stains that do not contain one. Mildew can be effectively
cleaned with a 3 to 1 ratio of water to bleach. A much stronger solution maybe
necessary in extreme cases of neglect. Proper surface preparation and cleaning
are crucial for mildew prevention, in addition to using a top quality primer
and acrylic latex finish paint. Acrylic latex finish paints are the most mildew
resistant. Again, good surface preparation and painting are your best allies
in preventing mildew growth.
Peeling occurs on a variety of surfaces and is directly linked to moisture
and inadequate surface preparation. Understanding different surfaces and how
they react to moisture and coatings will greatly reduce the risk of this common
paint problem. Remember: sand, patch/repair, prime, caulk and painting in shade
is the best process to prevent peeling.
Rusting occurs when metal is exposed to moisture and oxygen. Any metal surfaces
should be completely sealed with a rust inhibited primer. If rust appears through
painted surfaces, it should be wire brushed to bare metal or treated with a
coating that will harden it. Two coats of a top quality rust inhibited alkyd
or acrylic latex primer should be applied to metal surfaces once the rust is
treated or wire brushed away. Rusty nails that bleed through surfaces should
be reset, coated with a top quality rust inhibited primer, patched or caulked,
primed and painted with top quality coatings.
Sagging and running occur when paint is applied over glossy surfaces, excessive
thinning, too much paint on the surface, paint being applied to a dirty surface
or being applied in weather below the recommended temperature. Proper application
of paints and surface preparation will eliminate sags and runs.
Wrinkling is caused when thick paint is not brushed out and the under part remaining wet while the surface layer dries. Avoid covering surfaces with one thick coat when two are required and you should be fine.