There are powder coatings, liquid coatings, ultraviolet light-curable coatings and electrodeposited coatings, not to mention waterborne, solventborne, one-component, two-component, epoxies, polyurethanes, alkyds-and the list goes on and on. Are all of them really necessary?
Consider the many different types of environments that coatings must withstand before answering that question. For example, a silicone coating for steel must withstand temperatures as high as 1,200°F in a furnace. An automotive polyurethane clearcoat must be acid resistant to protect cars from substances like bird droppings and acid rain while maintaining a high-gloss finish. Military aerospace coatings must have a matte finish and be able to provide corrosion resistance on an aluminum aircraft that sits on an aircraft carrier for up to six months during a deployment in constant sea salt spray.