A new antimicrobial compound, which destroys microbes upon contact, is imbuing coatings for finishing surfaces with germ-fighting capabilities. By incorporating this powerful chemical, coatings are now deterring the spread of germs on surfaces in hospitals and doctors' offices, as well as in home kitchens, bathrooms and children's rooms.

And coatings for metals are not the only use for this long-lasting, inorganic compound. According to AgION Technologies, the Massachusetts-based biotechnology company that developed the antimicrobial additive, the compound "has been successfully and cost-effectively incorporated into fibers and fabrics, molded plastics, plastic films and coatings for metals, with proven effectiveness and safety." For example, Adidas already offers athletic equipment, footwear and apparel with the antimicrobial substance.

The compound is called AgION antimicrobial, a name combining the atomic symbol for silver, Ag, a natural antimicrobial agent, and "ion," referring to the ions from the silver that divide, attack and kill microbes. Aside from silver ions, the compound also contains zeolite, an inorganic ceramic element, which holds the silver ions and slowly releases them for long-term protection against germs.

In the presence of moisture, the zeolite pumps out silver ions in exchange for sodium ions from the environment. As the environment becomes more humid and more welcoming to bacterial growth, the zeolite discharges more silver ions, although there is a maximum release rate that it will not exceed even under extremely wet conditions.

Coatings with this antimicrobial compound are already protecting surfaces in the healthcare industry. For example, the new City of Hope's Helford Clinical Research Hospital in Duarte, California, uses antimicrobial powder coatings on its ductwork, door handles and hardware and push plates. Additionally, other hospitals and clinics are considering the use of antimicrobial powder coated materials on cabinets, counters and other surfaces in emergency, surgery and patients' rooms. Moreover, many types of medical equipment, from surgical scissors to exam tables, can be made from AgION-coated steels.

"While it is not a good idea to coat our entire world with antimicrobial substances," says Marjorie Kelly Cowan, Ph.D., professor of microbiology at Miami University in Ohio, "we are looking for any help we can get in eliminating microbes from the hospital environment and food preparation and serving areas."

The compound has already been deemed safe for food preparation areas by two organizations. The Food and Drug Administration (FDA) approved it as an acceptable additive in all polymers that touch food, while the National Sanitation Foundation endorses its use in food contact and food area applications.

Products that come into contact with food, such as refrigerators and ice cube-makers, are already being covered with coatings that incorporate the antimicrobial substance. For example, Bosch is protecting its refrigerator inner walls and door linings with an AgION-fortified powder coating. While Mile High Equipment Co. of Denver, the manufacturer of "Ice-O-Matic" commercial ice making equipment, is applying the antimicrobial compound to its Ice Series ice cube-makers.

The HVAC industry has also found various uses for coatings containing the AgION substance. Honeywell Corporation is using the special coating on portable, air-blown humidifiers, which use wicks to absorb water and are prone to germ growth. By including the application of the AgION compound in the manufacturing process for Honeywell and Duracraft humidifier filters, Honeywell Consumer Products is combating the surface growth and migration of bacteria, mold, fungi and algae.

AK Coatings Inc., a subsidiary of AK Steel Corp., is also protecting HVAC systems with AgION-reinforced coatings. In fact, AK Coatings says that the Environmental Protection Agency (EPA) has recently registered the use of its AgION antimicrobial steel compound in HVAC systems, making the company the sole supplier of coil-coated steels made with an antimicrobial, antibacterial coating for commercial, industrial, and residential heating and cooling applications.

According to AK Coatings, its special coated steels are made by first mixing the silver zeolite powder into an epoxy resin. The resin is then placed onto the steel using one of two methods—roll coating or powder coating, where the resin is ground into a fine powder that is electrostatically charged and sprayed onto the steel. The company says that treated surfaces will virtually eliminate most types of microbial contamination within three to four hours, with coating life dependent on the application and surface wear.

AK Coatings has already inked two separate deals with spiral duct-maker Lindab Inc. and Seal-Tite, maker of low-leakage duct, pipe and fittings. The partnership allows Lindab to make round, nonresidential ductwork with AgION antimicrobial precoated steel. And under its agreement with AK Coatings, Seal-Tite can manufacture its "Seal-Tite Rx" line using galvanized steel precoated with an epoxy incorporating AgION.

Seal-Tite says the antimicrobial agent can withstand multiple washes, effective for as long as the coating is on the steel. The coating reportedly resists fingerprints, watermarks, discoloration, staining and even scratches less than ¼ inch. The Seal-Tite Rx product is made for trunk duct and fittings, return air products, plenums, filter frames, drain pans, and pipe with a top operating temperature of 300°F, say company officials.

Additionally, AK Coatings is field-testing its antimicrobial powder coatings in a concept home in the Los Angeles area. The company is assessing the coatings' effectiveness in high-contact areas on a wide range of surfaces, including door knobs, handles and push panels, as well as on metal panels and railings within the home's elevator.

And while the AgION antimicrobial compound may still warrant some testing, its active ingredient—silver—has long proven its potency in suppressing the growth and proliferation of a wide range of microorganisms, such as bacteria, mold and mildew. In fact, Ancient Egyptians relied on silver particles to fend off fungus, mold and other microorganisms from food supplies. Meanwhile, the Phoenicians protected water from germ contamination by storing it in silver vessels.

Another huge advantage of silver is that germs cannot develop immunity to its debilitating effects through overexposure. This is because silver is inorganic, unlike commonly used antibiotics, which are organic and generally use only a single mechanism to control microorganisms. In comparison, inorganic antimicrobials kill organisms through multiple mechanisms, such as damaging cell walls, stopping cell multiplication and cutting off respiration. Furthermore, since inorganic and organic antimicrobials work very differently, any resistance to inorganics should not trigger resistance to organic, therapeutic antibiotics.

Users of AgION should keep in mind, however, that coated products still need to be cleaned to clear surfaces of harmful microbes. But as the AgION Technologies slogan claims, users can rest assured that "if this is on it, millions of bacteria aren't."

Sources: War on Germs Bolstered by New Powder Coating Product for Finishing Surfaces
The Powder Coating Institute Press Release, Jan. 31, 2003
http://www.powdercoating.org/media/pressreleases/war.htm

Germ Warfare
Wayne Johnson
Snips Magazine, Feb. 1, 2003
http://www.snipsmag.com/CDA/ArticleInformation/features/BNP__Features__Item/0,3374,92933,00.html