Protect yourself from the dangers of Isocyanates

New refinish technologies, such as waterborne basecoat systems, haven’t reduced the risks from isocyanate compounds. It’s still essential to take precautions, says Richard Nathan, chairman
of the Australian Heavy Vehicles Repairers’ Association.

Isocyanates and solvents are highly reactive organic chemical compounds. One of their most common industrial applications is a liquid, pre-polymer found in many paint formulations, including some refinish products. An isocyanate hardener or activator is added is to two-pack paint. Isocyanates are powerful irritants to the mucous membranes of the eyes, gastrointestinal and respiratory tracts, and direct skin contact can also cause inflammation. They can also cause asthma.
Although working with isocyanates and solvents is a fact of life in this industry, it doesn’t mean that you have to take risks.

New generation products

Although making the switch to a waterborne basecoat system significantly reduces solvent emissions, it doesn’t reduce isocyanate emissions. Neither waterborne or solvent-borne basecoat systems require isocyanate catalysts to cure, however both basecoats are generally finished with a two-pack solvent-based clearcoat which uses isocyanate hardener.

Exposure symptoms

Not taking the necessary precautions and subsequently being exposed to isocyanates may lead to allergic sensitisation, which could effectively end the career of a spray painter. Early signs may include runny/itchy eyes or nose, later developing into a wheeze, chest tightness (often occurring outside working hours in the evening or early morning), breathlessness or coughing.
 
Avoiding exposure

Treat paints with care, handling in accordance with their material safety data sheet. It’s important to note that the greatest risk of sensitization comes from inhaling vapour, spray mist or dust containing isocyanates. Safe working procedures and access to appropriate PPE solutions are available to protect technicians during the entire refinish process – but these are only useful if they are actually worn.

There is exposure danger outside the spraybooth (for example when mixing paint or cleaning spray guns), as well as inside. Only spray in an enclosed and adequately ventilated spraybooth capable of containing all paint emissions, maintained in top condition. Be aware that airborne isocyanates remain at high concentrations after spraying – generally for ten minutes or more, even with the ventilation system running.

Uncontrolled conditions

There have been many reports of trucks and machines that do not fit into a spraybooth being painted in the open. It is illegal and dangerous to spray in uncontrolled conditions. Spraybooths must comply with AS/NZS 4114.1:2003 and 4114.2:2003, and must have development consent from your local council.