Safer is Always Better
Many safety issues surround polyurea coating handling and application. Appropriate personal protective equipment (PPE) should always be used according to the polyurea coating system and the application equipment used. The safety of applicators, observers, and unknowing passersby is critical, as underscored by OSHA regulations.
The use of PPE cannot, and should not, be the only way to stay safe. The real risk to the polyurea coating spray applicator stems from the actual chemistry itself. These materials are reactive. Even though they can be touted as environmentally friendly once cured, they must be respected and handled with caution during application. Safer formulations should be available to applicators choosing to limit risk exposure while handling and applying the coating.
Methylene Diphenyl Diisocyanate (MDI) adds another facet to the safety issue. While MDI has a variety of forms, it’s well known that exposure to vapor or small particle MDI can cause sensitization, health-related problems, and death. To date, there have been at least four deaths attributable to MDI overexposure. The federal government issued a report after the causes of the deaths had been investigated. Tragically, the investigation was limited to exploring the circumstances surrounding these deaths and the PPE that should be used in their light, not what can be done to mitigate and reduce these risks from an equipment or application method viewpoint.
Alternative application methods and/or techniques, along with different equipment options, could greatly reduce risks arising from spraying polyurea-type coatings. However, large equipment manufacturers have no incentive to bring attention to such possibilities, since employing safer spraying parameters would include not purchasing or using the equipment they presently offer.
Common sense safety precautions include covering the skin, wearing eye protection, and using a National Institute for Occupational Safety and Health (NIOSH)-approved respirator. When spraying isocyanate-based (MDI or other) material, wear a respirator at all times; and, if spraying in a confined space, a supplied air respirator.
But don’t only consider respiratory protection in assessing the equipment necessary to manage the health risks posed by spraying polyurea types of coating systems. The increased risk of skin contact from spray mist when spraying polyureas, polyurethanes, and polyurea hybrid materials using high pressure spray equipment is also a considerable concern.
Anyone having experienced high pressure spraying, hot spray, is familiar with the mist cloud that forms around the spray area and moves with any air movement. This mist contains reacted, reacting, and unreacted particles of isocyanates, amines, polyols, or other additives included in the original formulation. Therefore, it’s recommended that not only the skin surfaces of the body be fully covered, but also that a full-face respirator be used to protect the eyes and facial skin from the coating mist moving around the sides of protective eye wear or face shields and being deposited onto the skin. A hooded suit, or head sock, may also be worn to protect the heads of those within the spray area.
The link between particle size and potential health risks is not generally discussed in trade publications. In fact, there is a direct relationship between smaller particle size and a higher likelihood that the particle could pass through, or around, safety equipment and/or be deposited on something that is touched later when the user is not wearing gloves. Exposure to the chemicals can result before, during, or after actual spraying. It’s imperative to consider personal protection during the entire process: arrival, taping or masking out, equipment setup, substrate preparation, test spraying, actual job spraying, unmasking or untaping, clean up, and use.
Since smaller particle sizes are suspended in the air more easily, and are more easily passed through or around safety equipment, larger particle size application equipment should be considered a safer alternative—that is, cold spray and warm spray low-pressure equipment.