A Fresh Coat
U.S. Manufacturers’ use of low-volatile organic compound paint is improving air quality
By Hank Godshalk
This editorial originally appeared in the September 2005 issue of Environmental
Protection, Vol. 16, No. 7.
Virtually all metal product manufacturers insist that their products perform well and look good. Often, a key factor in determining if these goals are met is the coating they receive before leaving the factory. These same companies also want their factories to meet all U.S. Environmental Protection Agency (EPA) air quality standards and to be
healthy environments for their employees. In many cases, this is also a function of the coatings applied to the products.
From a marketing perspective, appearance is critical. How a product looks conveys an important message about
its value, quality, and performance expectations. Companies manufacturing items as diverse as furniture, tool
boxes, lockers, generators, and construction equipment all insist that their products arrive with a consistent
color, texture, and sheen. The color of some products is actually a legally protected identification feature. Today,
a growing number of companies are producing painted glass products with the same appearance mandates.
Many metal products must perform in a surface-hostile environment. Portable metal chairs, for example, are
constantly being kicked, spilled upon, and knocked over. Construction equipment often sits outside exposed to
hot sun, cold snow, and abrasive dust and sand. Many products, such as automotive or industrial components,
are primarily coated for protection rather than long-term appearance since they are hidden from view when
installed, and because their appearance is relatively unimportant.
The manufacturers of all of these products want a coating that is as resistant as possible to chipping, scratching,
and environmental forces. Achieving all this used to be fairly simple. An air-dry or bake-enamel, solvent-based
coating was applied to these products. These kinds of coatings hold their surface appearance and are resistant to
chemicals, moisture, and abrasion. Unfortunately, solvent-based coatings also give off odors and air
contaminants while being applied and while drying, resulting in environmental and workplace air contamination.
But for many years, manufacturers using these coatings had few options. Other coatings failed to deliver the
same production, quality, appearance, field performance, and economic requirements that were achieved by
Along Came the Act
The Clean Air Act passed in 1970, and things began to change. The statute was not targeted only at the coating
industry but the Clean Air Act did mandate that coatings could only contain VOC (volatile organic compounds)
levels of 3.5 pounds (lbs.) per gallon sans (without) water. Then, the most commonly used solvent-based paints
ranged up to 6.0 lbs/gallon sans water. Actually, different federal and state VOC requirements were permitted,
creating additional challenges for many manufacturers and their paint suppliers.
At its core, the difference between solvent-based paints and waterborne paints is the difference in their water
levels. For example, the VOC content of solvent-based paint can range from 2.5 lbs./gallon sans water up to 6.0
lbs./gallon sans water, depending on the formulation of the paint. By excluding water from the calculation, the
results reflect only the volume of VOCs and non-volatile solids. During the production of waterborne paint,
however, the organic solvents are, in part, replaced by water, resulting in VOC levels between 1.5 and 3.5
lbs./gallon sans water.
Industrial manufacturers realized that reducing the coating-related VOCs in their factories would also help lead
to plant-wide compliance with the Clean Air Act and improve factory conditions. If this could be achieved using
waterborne coatings, they could comply with VOC requirements without sacrificing their significant investment in
liquid paint lines, which often include integrated wash lines, spray paint booths, and drying ovens.
They saw other advantages, too. Paint booths are equipped with filters that absorb any over-spray. When they
are replaced and discarded, solvent paint-laden filters must be treated as hazardous waste. When waterborne
paint is used, the filters are less hazardous as long as spontaneous combustion of the oxidizing vehicle is guarded
against. In addition, the risk of fire with solvent-based coatings disappears with waterborne coatings, providing
both a practical advantage and a financial incentive in the form of reduced insurance premiums. Waterborne
coating manufacturers reached the same conclusions and began making significant research and production
investments to create high-performance, low-VOC, waterborne liquid coatings that would empower
manufacturers to meet market requirements and improve working conditions.
Underlying this trend in low-VOC coatings was a mutual understanding by industrial and coating manufacturers
that any new coating also had to meet all the necessary economic and field performance requirements. No
company could afford to adopt a coating that made a poor impression on the market, failed during use, or was too
expensive to apply. For example, colors had to match that of the solvent paint being replaced, and color
consistency had to be exact from batch to patch. Some companies market products that feature a metallic
appearance as a key focal point. This product category had to be filled by waterborne companies as well.
Trial and Error
This was not an overnight effort. Paint companies first tried to emulsify resins in water, but this proved
unsuccessful. Next came the use of water soluble-resins, which in the mid 1970s, allowed production of coatings
with VOC levels of 3.5 lbs/gallon sans water but this also was not sufficient. By replacing organic solvents with
water, VOC levels in a few coatings were reduced to as low as 1.5 lbs./gallon sans water.
In the mid-1980s came the adoption of latex polymerization with resins produced in water. This was suitable for
creating flat- and semi-gloss coatings with VOCs as low as 2.5 lbs./gallon sans water, but this technology could
not create high-gloss coatings.
Continued research led to VOC levels from 1.8 to 2.20 lbs./gallon sans water, but only in certain colors. New
color dispersions, introduced in 2000, solved these color limitations. The adoption of still newer resin technology
resulted in coatings with VOC levels as low as 0.3 lbs/gallon sans water. Recent research has led to waterborne
coatings with VOC levels near zero lbs/gallon sans water. These coatings are still under development to broaden
their application, but the potential is significant. A factory using waterborne coatings and consuming 24,000
gallons per year can further reduce VOCs by 4,000 gallons if near-zero can be perfected. This represents
$15,000 in raw-material savings.
While paint company labs were perfecting low-VOC formulas, the industrial market was still insistent that
production efficiencies had to be achieved. For example,”Just In Time” manufacturers must switch production
runs, and thus product colors, on short notice. Changing colors quickly to keep up with a rapidly changing
manufacturing schedule is easily achieved with waterborne paint because the lines can be cleaned quickly
between colors by flushing them with water.
In the factory, wasted paint means wasted production costs. The measurement of how much paint actually ends
up on the surface of a product is called transfer efficiency and is also a determination of how thick the coating is.
High transfer efficiency occurs when most of the paint is on the surface but at the minimum film-thickness
required for tested field performance. When modern paint line equipment is used, waterborne paint can be
applied with a very high transfer-efficiency rate that prevents overspending due to paint waste.
Many products have very small crevices and protected areas that can’t be coated in a paint booth and must be
touched up later. Solvent-based paint operations usually accomplish this touch-up process using small aerosol
cans. This adds to air contamination and also requires a can disposal cost. Using waterborne paint, this touch up
can be achieved with small, secondary spray booths.
The growing importance of ISO certification among industrial manufacturers has, of course, increased the
demand for vendors who are also ISO certified. Recognizing that an ISO rating will impact their ability to market
paint, many waterborne-coating manufacturers are seeking, or have already received, their own ISO certification.
Waterborne-coating companies are also attacking the Hazardous Air Pollutants (HAPs) issue. It is now possible
for companies that operate high-volume production lines, and want to ship products as quickly as possible, to
purchase a HAPs-free, quick-drying, air-dry coating. It is also highly moisture resistant, which is a requirement
for many products that operate in both indoor and outdoor environments where there is a great deal of moisture
Hank Godshalk is the founder of Finishes Unlimited, Inc., a manufacturer of waterborne air-dry and bake-enamel paints used primarily to coat metal, wood, plastic, glass, and concrete. The company is based in Sugar Grove, Ill. Godshalk has a BS in chemistry from Franklin and MarshallCollege. He spent his early years with DuPont as a member of the Marshall Point Research Laboratory team assigned the objective of converting General Motors to the use of a more durable acrylic laquer system. In the mid-50s, Godshalk moved on to a number of other technical and general management positions with companies in the pigments and dispersions areas of coating technology.