Low VOC Paints, Stains and Finishes

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Low VOC Paints, Stains and Finishes

Paints, stains and finishes protect materials and add beauty to building exteriors. Here’s a guide to choosing products that are beautifully sustainable, too.
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Friday, September 18, 2015 - 8:30am

We expect a lot out of the coatings that protect siding, trim and other parts of a building exterior. Paints, stains and finishes must be resistant to moisture, mold and the constant exposure to UV radiation. And of course they must add beauty to the materials. Modern chemistry allows coatings to perform, but not without costs. Most paints and finishes are high in embodied energy, and since home exteriors are repainted frequently—on average, every five to 10 years—coatings can add significantly to a building’s carbon footprint. Consequently, choosing a durable product, proper application and maintenance are imperative.

Many coatings contain volatile organic compounds (VOCs) and toxic chemicals that threaten the health of workers in manufacturing facilities, contractors applying the materials and people exposed to them inside or outside of buildings. Architectural coating products also present a disposal problem.

Fortunately, the industry has undergone a transformation in recent decades. The first big change was the phase-out of lead pigments, banned in 1978. The industry has moved away from oil-based solvents; today, the vast majority of all architectural coatings are water based. These contain a fraction of the VOCs and much lower embodied energy.

The Chemistry of Paint

Paints consist of pigments, binders, solvents and additives. Before it was phased out in 1978, lead was a commonly used pigment that enhanced paint’s durability. Titanium dioxide is the most widely used paint pigment today; it is also used in sunscreens and cosmetics. TiO2 production is energy intensive and may account for a large percentage of the embodied energy in paints. (The EPA estimates that the total emissions from domestic TiO2 production in 2006 equaled 3.6 metric tons.)

As the word implies, binders help hold the pigments together. Most high-end water-based paints contain synthetic acrylic resins as the binder. These paints perform extremely well, and although acrylic resins are made from petroleum, water-based paints—also called “latex-based” paints—don’t have the same environmental issues as those that use oil as a solvent, which can be a significant source of VOCs in coatings. Additives include biocides, fungicides and agents which enhance performance. Heavy metals such as cadmium are used as drying agents.

Some of the problem VOCs found in conventional paints include formaldehyde, benzene, acetone, cyclohexane and xylene. Not only are these compounds harmful to health, they accrue in the atmosphere, adding to the greenhouse effect.

The EPA limits VOC concentrations in architectural coatings; for instance, the limit for exterior coatings is 380 grams per liter (g/L); the limit for clear and semitransparent stains is 550 g/L. Some states, regions and counties have set even stricter standards; for example, South Coast Air Quality Management District (SCAQMD), the air pollution control agency for the Los Angeles area, limits VOC levels in architectural coatings to 50 g/L.


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