Workplace Safety Guides

   Safer Spray Painting Systems

    

One way to make spray painting safer is to change the content of the coating material to meet the double protection objective. Actually, cutting the amount of overspray in an operation will probably require an equipment change. Where compressed air delivery systems used to be the rule, now airless heated paint and electrostatic systems are able to significantly reduce the overspray problem.

Every system has its pros and cons. Compressed air systems are excellent for frequent color changes, will coat almost any shape, will apply water-borne paints, and can be used on automatic gun movers.

But they waste large amounts of paint. Often they require more energy to run the bigger exhaust systems necessitated by the overspray. Airless guns use hydraulic pressure to force the paint through a small opening and into the air. The process can be compared to a garden hose nozzle that atomizes water by forcing it through a small opening under pressure.

Airless sprays are often heated as well. Overspray is greatly reduced over compressed air delivery. Heavier coats can be developed without runs or sags. Hot airless may produce a higher gloss, too.

Airless guns may clog a bit easier because of the smaller opening used. The systems are more expensive, have a more limited pattern in flow adjustment, and have some overlapping difficulties. There is danger of serious injury to painters who misuse this equipment. Injection of paint under the skin can have serious consequences.

Electrostatic guns electrically charge the paint as it leaves the gun, which attracts it to the grounded object to be painted. This substantially reduces overspray and possibly reduces ventilation requirements. Electrostatic application provides excellent wraparound and coating of sharp edges. However, it may not coat recessed areas or other null points on the object.

Suppliers and their trade group, The National Spray Equipment Manufacturers Association, can help you select the system to best protect your painters and your products.

If you can't eliminate or alter the overspray, you can keep it out of the painter's breathing zone and the rest of the area with proper ventilation. This is most often done with spray booths. Whether small booths or large ones, they all work by directing cleaner air past the worker toward the product and into a collection point or exhaust hood.

Larger products may require a top-to-bottom airflow to work effectively. Designers of good ventilation systems must consider a number of complex variables, such as air velocity, air cleaning techniques, and degree of enclosure of a space. It's work for a qualified engineer.

Another way to reduce worker exposure is to isolate him or her from the process. This can be done by automating the system, which is expensive to start but cheap to operate, or by personal protective equipment for the painter. A respirator, gloves, overalls, and hat provide a protective coating for the painter and isolates him or her from the overspray.

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