Green Coatings Truths and Myths
Just about everyone these days has a "green" product
in the coatings industry. There is 'Eco this' or 'Enviro that'
labeling. Manufacturers splash exotic colors all over their slick
brochures with lush green leafs and tranquil waterfalls cascading
in the background. They inform us how their coatings are environmentally
friendly and will help protect our fragile ecosystems. But are
these coatings really environmental at all? Not always.
Many environmental organizations such as the U.S. Environmental
Protection Agency (EPA), South Coast Air Quality Management
District (SCAQMD), Leadership in Energy and Environmental Design
(LEED) and Green Seal have established a number of well intentioned
but erroneous standards regarding VOCs. Generally speaking,
VOC levels for interior latex paints are 150 g/L for non-flat
paints and 50 g/L for flat paints. Exterior paints are typically
200 g/L for non-flat and 100 g/L for flat paints.
But what does this all mean? Perhaps it means very little because
VOCs are only calculated on the base white product and without
the colorant system. For example, a 150 gram VOC base white with
the addition of a red oxide pigment could increase to 160 g/L.
Universal colorants can have more than 160 grams per liter of
VOCs because of high glycol levels. If a painting contractor
is coating a surface with an accent color such as yellow, three
to five coats are often required to get decent hide. If you combine
the VOCs from the base polymer with the universal colorant system
then a great deal more VOCs are being emitted from the combined
VOCs can cause headaches, allergic reactions and health problems
in humans if inhaled and contribute to the formation of troposphere
ozone, smog and global warming.
Energy efficiency should be considered a criterion for green
coatings. Energy-efficient coatings utilize sophisticated heat-blocking
pigments that refract the sun's visible, infrared and UV radiation
away from the substrate, thereby reducing radiant heat transfer
within a property. If a property can remain cool, there is
a lower demand for cooling systems, which, in turn, decreases
the demand on utility companies to burn fossil fuels to run
generators. It is the burning of fossil fuels that contributes
to smog and ozone depletion. Typical retail-bought paints,
which are specified on most exterior walls, are not heat-reflective
or energy-efficient. They can contain high levels of VOCs,
may not be durable and often do not help protect the environment.
Performance should be an important feature of an environmental
coating. A long-lasting coating means less paint cycles, which
means fewer VOCs are emitted. The physical performance of latex
paints depends on a number of variables such as quality of
pigments, film build, polymer and sheen. Highly reflective
Mixed Metal Oxides (MMOs) reduce surface temperature, which
extends the life of the coating. High film build coatings last
longer than low film build simply because of greater thickness.
One-hundred-percent acrylics last longer than styrene and PVA
acrylics. High-sheen coatings last longer than flat-sheen coatings
because they contain fewer fillers and extender pigments.
Retail latex paints typically last 3-7 years between repaint
cycles. Some high-performing elastomerics and thermoplastics
that utilize heat reflective technology can last more than 20
years between recoats. The longer a coating lasts, the better
it is for the environment, and this is the reason why it should
be considered a criterion for a green coating specification.
Recycled paint has been a green practice for a period of time
in the United States. However, why aren't the paint containers
also recycled in a similar fashion as they are in other countries
such as New Zealand or Canada? It is estimated that 95% of
all paint cans in the U.S. end up clogging landfills. Many
paint cans are manufactured from polyethylene, which can be
recycled into garbage bags, soda bottles or shopping bags.
Definition of a Green Coating System
Defining a green coating within the United States is like pulling
a confused rabbit out of a magic hat. Anyone can conjure up
his or her own set of standards. Green coating standards must
include a more comprehensive look at VOCs, energy efficiency,
long-term performance, and recycling latex polymers and containers.