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Do I Need to Use Paint
Primer?
Paint colors, dyes and compositions are getting better all the
time. Effects that would have been unthinkable just a generation
ago are becoming easier than ever to achieve, from special matte
finishes that resemble suede to effortless crackle glazes that
make faux effects a cinch. One thing paint cannot do terribly
well on its own, however, is bond to every possible surface
without a little help. This is where paint primer comes in. If
you have come online in search of vetted and reliable info on
which primer to use and when, the following survey may be of
some use. |
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The basic rule of thumb
for paint primer is that it is necessary whenever you cannot create
a totally flat surface for painting. Surfaces with cracks, holes or
depressions that aren’t properly sealed could greatly reduce the
paint’s ability to set effectively, so inherently porous substrates
such as wood, drywall and concrete tend to come with primer
recommendations attached. The natural holes in such materials can
create an uneven surface for painting. But each of these materials
requires somewhat different care, and it pays to understand what
distinguishes one from the next.
Wood is the most common surface for paint primers, a fact that is
hardly surprising considering its organic nature. The reason you
always want to prime wood before painting is twofold – to protect
the paint, and to protect the wood. A number of modern paints dry
into proper color and hardness via evaporation, meaning they require
the water to find its way into the atmosphere. The problem is that
wood is a notoriously thirsty substance, and it is easy for water to
get absorbed into the grain itself. Often the paint will begin to
pucker and peel if the wood isn’t dry, making it necessary to scrape
and start over. Paint primer creates a watertight seals between the
two and ensures the paint has a smooth and adhesive surface with
which to bond.
A second reason you always want to prime a wood surface is because
the same absorption can quickly undo your attempts at an even coat.
Lighter paint colors especially will often reveal the telltale
whorls of wood grain even after several passes, requiring you to
paint over and over for a truly solid hue. Although you could indeed
take the hours necessary to paint repeatedly, often you can achieve
the same effect with a few fast coats of primer first. The advantage
extends well beyond mere convenience – primer tends to cost far less
than paint, easing your financial burden in the process.
The wood itself can be injured without a primer in place. Although a
negligible amount of water is absorbed during drying, considerably
greater amounts may leech into the grain if that painted surface is
exposed to the elements. Without a primer in place, it’s not unusual
for repeated thunderstorms to take their toll, creating devastating
conditions for mold, mildew and warping. Although many people
consider outdoor paints to be waterproof, often they are anything
but – their hardy nature derives from their ability to absorb
rainwater with ease.
Of course, paint primer is recommended for a variety of other
materials as well. In concrete and drywall, for instance, you simply
want to seal the surface and create a solid bond without having to
worry about similar problems with drying and moisture. For metals –
especially those prone to rust – a paint primer can protect the
surface itself and keep moisture locked out. Plastics too can
benefit from a coat of paint primer, particularly if they are porous
in nature or you are putting a light color over a darker one.
Finally you may need primer to marry two different paint types
together, as when you apply latex over oil paint.
One thing primers are decidedly not for is hiding blemishes or
“sealing in” mold and mildew. If you are working with a material
that may have absorbed or produced an organic population such as
this, it is essential to clean thoroughly before you paint. Dry
everything for several hours and wait to see if the problem recurs.
It is better to discard a rotted plank than to use primer to delay
the inevitable! |
