The Waterborne Coatings Revolution

by Lane Blackburn   

V.P. Architectural Marketing, The Sherwin-Williams Co.

While the so-called "era of VOC restrictions" now appears not to be nearly as limiting as when it initially appeared in 1990, architectural and industrial paint and coatings manufacturers are not slowing down in the research and development of new generations of waterborne coatings.

Despite less stringent requirements in federal clean air guidelines and volatile organic compound (VOC) reduction levels that will allow some alkyd products to remain on the market, waterborne coatings remain the industry's future. It's important for specifiers to keep this in mind when developing comprehensive specifications, especially in certain states such as New York, New Jersey, Oregon, Washington and California, to name only a few. Your paint supplier will be able to keep you abreast of the constant state and local changes occurring as a result of this legislation.

Federal guidelines

Regulations protecting the environment are increasing. Paint, especially solvent-based formulas containing large quantities of air-polluting VOCs, is a target of these regulations. Since the 1970 inception of the federal Clean Air Act, VOCs have been a target of air quality programs.

In 1990, a federal rule proposed maximum VOC content levels for architectural and industrial paints and coatings. Originally, an extension of these guidelines would have required paint manufacturers to further reduce VOC content in their products an additional 25 percent below 1990 levels this year. That is no longer the case. The suggested guidelines, proposed to go into effect sometime in 1999, are now less stringent, particularly for architectural and industrial coatings. The accompanying chart represents the current proposed EPA framework for selected architectural and industrial coatings. The complete list has many additional specialized finishes.

Waterborne coatings must also comply with the Federal Rules for VOC Compliance. For example, interior flat latex wall paints must have a VOC equal to or less than 250 g/L. Exterior gloss latex enamels must comply with 380 g/L or less.

The amended rules permit a few solvent-based products, such as certain oil-based house paints and primers and interior primers and finishes to remain in existence, as long as they fall within the VOC guidelines. But most would be unavailable under these proposed regulations. Those that remain may dry slowly, apply with difficulty and potentially yellow. This, however, will not stop the development of new waterborne alternatives, which are offering even better performance than their solventborne counterparts. This holds true in both the architectural and industrial markets.

Architectural coatings

This new generation of environmentally neutral, low-VOC waterborne architectural coatings is harder and more weather resistant than traditional latex paints. Those already introduced have greater durability and dry faster than alkyds with much lower odor. In fact, a new category of latex low-odor paints on the market permits painting in occupied areas, such as classrooms, school hallways and cafeterias.

Latex interior flats are gaining close to 100 percent acceptance in high-traffic areas in both commercial and residential settings. There is, in fact, a flat latex wall paint that supersedes interior flat alkyds with regard to stain release and washability, and durable waterborne enamels that offer the hardness and appearance of an alkyd but apply faster and easier without yellowing.

On the other hand, interior latex stains and varnishes are not yet performing as well as traditional solvent stains and clears. The argument is that these products are still more difficult to apply and that they aren't as durable as their solventborne counterparts. In the near future, new products in this segment should match the quality of today's solvent-based interior wood finishes.

Most exterior waterborne coatings specified are successful, excelling particularly in the area of color and gloss retention. Negative factors include weakness in adhesion over marginally prepared surfaces and application in low temperatures.

Waterborne coatings face two performance obstacles. The first is that of limits on low-temperature application, as previously mentioned. Though waterborne exterior products that permit application at temperatures as low as 35F have been introduced by at least one manufacturer, as a general rule most application is limited to temperatures above 50 degrees. This low-temperature application feature allows jobs to be completed later in the fall, or begun earlier in the spring.

The second obstacle is that of adhesion onto marginally prepared surfaces -- both interior and exterior. Waterborne coatings generally don’t have the adhesion of traditional alkyds when applied over grimy, chalky, peeling surfaces. Consequently, these coatings require greater surface preparation in such situations, often increasing work time and the associated costs. But in light of the VOC-reduction levels and continuing R&D in this area, these obstacles also are being addressed.

The most important thing to bear in mind is that waterborne coatings should be a first choice, as the alkyd options are becoming increasingly less advantageous in light of the overwhelming benefits new waterborne technologies bring to the specifier and building owner.

High Performance Coatings

It's not only in architectural applications that waterborne coatings are proving their merits. In commercial/industrial applications as well, high-performance waterborne coatings are being specified more frequently due to enhanced application and performance characteristics. In these applications, corrosion control and heavy duty durability are key.

New polymers allow today's waterborne coatings to be more abrasion, chemical and moisture resistant. Complementing these resins are new additives that help the coatings to overcome flash rusting, foaming and other problems that were common to the first generation of waterborne coatings.

Waterborne coatings developed for industrial applications are also being specified more frequently due to enhanced application and performance characteristics. New polymers allow today's waterbornes to be more abrasion, chemical and moisture resistant. Complementing these resins are new additives that help the coatings to overcome flash rusting, foaming and other problems that were common to the first generation of waterborne coatings.

To address a variety of applications and corrosive conditions, a number of waterborne alternatives are available. They include water-based catalyzed epoxies, direct-to-metal (DTM) acrylics and waterborne dry fall acrylics. Such coatings might be used in HVAC, utility, commercial kitchen, meeting/banquet room, storage space or light industrial environments, among other areas.

Waterborne catalyzed epoxies are an upgrade from conventional latex or alkyd-based coatings, performing as well or better than their solvent-based counterparts. Like all epoxies, waterborne epoxies form a tight, dense film that is resistant to corrosion, mild chemicals, impact and abrasion. They are recommended for use as a finish coat to upgrade conventionally painted, high-maintenance areas where they function as a high-performance protection system for walls and floors that may be subjected to abrasion or impact -- such as heavy foot traffic or fork lift traffic.

DTM acrylics offer the convenience of water-based coatings with the performance qualities of conventional solvent-based systems. They have good durability, exceptional resistance to ultraviolet light (UV) and long-term flexibility. Recent technology advances have made possible acrylic coatings that are more chemical and corrosion resistant. The broad spectrum of performance capabilities of DTM acrylics makes them ideal for both interior and exterior applications. They can be used in areas with exposed ductwork, piping, steel columns or supports and galvanized walls, such as mechanical rooms and HVAC closets, and are also appropriate for use on metal railings -- like those found in stairwells.

Waterborne acrylic dry fall coatings are an environmentally acceptable alternative to traditional solvent-based ceiling coatings. They emit a very low odor during application, and have a low flash point. And, like all dry falls, they offer very high light reflectance and dry to dust within 10 feet. Waterborne acrylic dry fall coatings are especially well suited for spaces with pre-cast concrete or steel beam ceilings. They can save time and make application easier in an occupied space.

Challenges for all

The challenge for paint manufacturers is to provide products that work with existing substrates and application procedures. Smart manufacturers take this into account. It's already part of their strategic direction.

For Sherwin-Williams specifically, the current regulatory atmosphere is not driving product development and technology. It's done from the perspective of producing and supplying user-friendly products that offer improved productivity and better end user satisfaction in addition to environmental compliance.

The challenge, however, extends beyond paint manufacturers. While alkyds have ruled the commercial market, it’s time to get educated on the benefits of their waterborne counterparts and foster acceptance of these products.

It appears most painting contractors now use waterborne coatings and are happy with them. Some reluctance to switch still exists, particularly by "traditionalists" who swear by alkyds and claim that new waterbornes don't have the same durability or application characteristics of alkyds. In many cases, they haven’t tried the new products before making their decision.

Specifiers are best advised to stay close to their paint supplier's specifier representative. These individuals are attuned to the advances in technology and new product offerings. Learn from them and keep an open mind when it comes to any new products. Try the new waterborne coatings before jumping to any conclusions. You'll find most of the newer waterborne systems exceed the capabilities and application of traditional alkyd systems.

There will always be traditionalists who will perpetuate the notion that solventborne finishes are the best. The current federal clean air proposal will provide them with some low VOC alkyds but overall solvent-based coatings are a dying breed. We're in a waterborne revolution and there's no turning back.

by Lane Blackburn   

V.P. Architectural Marketing, The Sherwin-Williams Co