Millions of items ranging from cars to candy are covered by paint, plastic, varnish, chocolate, or some other type of coating solution. Often, the protection provided by the paint or coating is essential to the product, as with the coating of insulating material covering wires and other electrical and electronic components. Also, many paints and coatings have dual purposes; for example, the paint finish on an automobile heightens the visual appearance of the vehicle while providing protection from corrosion.
Coating, painting, and spraying machine setters, operators, and tenders control the machinery that applies these paints and coatings to a wide range of manufactured products. Perhaps the most straightforward technique is simply dipping an item in a large vat of paint or other coating. This is the technique used by dippers, who immerse racks or baskets of articles in vats of paint, liquid plastic, or other solutions by means of a power hoist. Similarly, tumbling barrel painters deposit articles made of porous materials into a barrel of paint, varnish, or other coating; the barrel is then rotated to ensure thorough coverage.
Another familiar technique is spraying products with a solution of paint or some other coating. Spray machine operators use spray guns to coat metal, wood, ceramic, fabric, paper, and food products with paint and other coating solutions. Following a formula, operators fill the machine’s tanks with a mixture of paints or chemicals, adding prescribed amounts of solution. Then they adjust nozzles on the guns to obtain the proper dispersion of the spray, and they hold or position the guns so as to direct the spray onto the article. Operators also check the flow and viscosity of the paint or solution and visually inspect the quality of the coating. When products are drying, these workers often must regulate the temperature and air circulation in drying ovens. Individuals who paint, coat, or decorate articles such as furniture, glass, pottery, toys, cakes, and books are known as painting, coating, and decorating workers.
Painting and coating workers use various types of machines to coat a range of products. Frequently, their job title reflects the specialized nature of the machine or of the coating being applied. For example, enrobing machine operators coat, or “enrobe,” confectionery, bakery, and other food products with melted chocolate, cheese, oils, sugar, or other substances. Paper coating machine operators spray “size” on rolls of paper to give it its gloss or finish. Silvering applicators spray silver, tin, and copper solutions on glass in the manufacture of mirrors.
In response to concerns about air pollution and worker safety, manufacturers increasingly are using new types of paints and coatings, instead of high-solvent paints, on their products. Water-based paints and powder coatings are two of the most common. These compounds do not emit as many volatile organic compounds into the air and can be applied to a variety of products. Powder coatings are sprayed much as are liquid paints and then are heated to melt and cure the coating.
The adoption of new types of paints often is accompanied by a conversion to more automated painting equipment that the operator sets and monitors. When using these machines, operators position the automatic spray guns, set the nozzles, and synchronize the action of the guns with the speed of the conveyor carrying articles through the machine and drying ovens. The operator also may add solvents or water to the paint vessel, thereby preparing the paint for application. During the operation of the equipment, these workers tend painting machines, observe gauges on the control panel, and check articles for evidence of any variation from specifications. The operator then uses a spray gun to “touch up” spots where necessary.
Although the majority of painting and coating workers are employed in manufacturing, the best known group refinishes old and damaged cars, trucks, and buses in automotive body repair and paint shops. Transportation equipment painters, or automotive painters, are among the most highly skilled manual spray operators, because they perform intricate, detailed work and mix paints to match the original color, a task that is especially difficult if the color has faded.
To prepare a vehicle for painting, painters or their helpers use power sanders and sandpaper to remove the original paint or rust and then fill small dents and scratches with body filler. They also remove or mask parts they do not want to paint, such as chrome trim, headlights, windows, and mirrors. Automotive painters use a spray gun to apply several coats of paint. They apply enamel or water-based primers to vehicles with metal bodies and flexible primers to newer vehicles with plastic body parts. Controlling the spray gun by hand, they apply successive coats until the finish of the repaired sections of the vehicle matches that of the original, undamaged portions. To speed drying between coats, they may place the freshly painted vehicle under heat lamps or in a special infrared oven. After each coat of primer dries, they sand the surface to remove any irregularities and to improve the adhesion of the next coat. Final sanding of the primers may be done by hand with a fine grade of sandpaper. A sealer then is applied and allowed to dry, followed by the final topcoat.