The object, its material and its use are critical information. The painting that people do around the home is often done with a water based paint and a brush. Or, one might use a spray can. Most likely, if you want your wooden flower box painted, you would do it at home with a brush as opposed to sending it to a professional woodworker. On the other hand, an automobile plant would use a professional spraying method and not the paintbrush and can of latex paint.
When shopping for items that are painted, it is often useful to know how they were painted. (This information can often be found in the product description or manual.) This is especially true of items that are going to get exposed to weather, be rubbed against other items frequently, or submerged in water. These factors may determine how well the paint stays on the item. Manufacturers choose painting applications according to what they are making, what highly specialized equipment and controlled environment is needed, and they are also concerned with environmental impact.
Two highly used coating techniques are waterborne (water-based) coatings and powder coating. Water-based coating. Also referred to as acrylic emulsions, these paints contain little or no organic solvents. Two techniques for applying water based pigments are spraying and dip-coating. Advantages: it has a wide range of applications, from wood furniture to the architectural trades; it has operational benefits of easy color blending and variable coating thickness choice; there are little or no harmful environmental emissions. Limitations: application and drying rate are sensitive to humidity; water in paint can cause corrosion of storage tanks and transfer piping, and possible rusting.
Powder coating. In this process, powder constituents are applied with an electrostatic spray gun and then the item is placed in an oven and heated to temperatures of 160 to 210 degrees. Advantages: It provides a tough, abrasion resistant coating; it is possible to apply thick or thin layers for higher quality decorative finishes; no mixing or stirring is needed; applications are steel, aluminum, zinc and brass. Limitations: requires handling of heated parts; complex parts are difficult to coat; difficult to incorporate metal flake pigments.
Recommendations when shopping for household items: metal racks and hanging hooks are better powder coated to avoid paint chipping; patio metal furniture stands up to the weather and elements best when powder coated; wooden furniture is more suitable to water based paint or stain, which offers more colors and finishes; wood and plaster decorations are best when painted with a water based coating.
In summary, pigments, stains and other finishes are applied commercially with specialized equipment, and are dependent on the type of material and use of the item being manufactured. When you are shopping for household items, try to find a description of how they were painted. Water based coatings are versatile and good for the environment, but powder coating is the best for metal objects. The right paint coating will protect and help your item will look nice for a long time.