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.
Whether someone spends $25,000 for a new car or $50 million on a new aircraft, they expect the coatings to provide protection and retain the aesthetic appeal that the product had when it was new. Purchasers should expect to pay a fair price for the coating, depending on the amount of protection the product provides: the more the protection, the higher the price. As the need for more expensive or less expensive coatings increases, so does the number of coatings.
Why is paint on your house different from the paint on your car, and why is aircraft paint different from automotive paint? Are use-specific paints really necessary? Why can't Boeing paint airplanes with an automotive paint? Part of the answer was mentioned previously: different environments. Think of an aircraft taking off from Las Vegas in the middle of summer at 110°F and within minutes it is cruising at 500 mph at 30,000 feet where the temperature may be very cold, say 50°F. Not your typical car environment. Sunlight has a detrimental effect on paint, and the sunlight at 30,000 feet above the clouds, versus sunlight filtered though the atmosphere at sea level, can be significantly different. It all comes down to different service environments.
Just look around your workspace and you will notice that almost everything is coated. From the calendar on your wall to your office furniture to your telephone, they all have coatings. Coatings that must perform a broad array of functions, and at a price you are willing to pay. It becomes more and more apparent why we have all these coatings.
An office furniture manufacturer could paint a metal bookcase with the same coating used on aircraft landing gear, but they don't need the same properties, and you would not want to pay for the un-needed performance. The bookcase, hopefully, will not be exposed to the same abuse as landing gear moving down the runway at 120 miles an hour.
Manufacturing processes also drive the need for coating properties. Coil coatings applied at line speeds of 200 fpm are applied in that fashion out of economic necessity. Coat-hanger coatings are electrodeposited in large batches, also out of economical necessity. Imagine trying to apply paint to a coat hanger with a hand-held HVLP spray gun. Not very economical, though it works great for cars.
Most likely, federal, state and local environmental regulations have forced you to change your coatings in the past 10 years to reduce VOCs and improve air quality. This is another driver for increasing the types of coatings on the market.
Coating manufacturers are currently striving to develop zero-VOC coatings with no HAPs. As environmental regulations limit coatings manufacturers, the challenge becomes even greater to formulate coatings that are environmentally friendly, yet meet the many stringent service requirements of the vast array of products that we want to paint.
So the next time you read about the latest and greatest coating and say to yourself, "Oh no, not another one," remember that there are reasons why we have so many coatings. And thank your coating manufacturer for dedicating its resources to further the development of coatings to meet our varied needs.