How are coatings getting greener?
Look up from your computer for a moment: Of all the things in your field of view -- furniture, books, appliances and even the walls and carpet -- how many have some type of coating on them? Are they painted? Do they have glossy or flat finishes? Are they painted or stained? If you think about it, it may be easier to count the uncoated things around you than all those that feature some form of cosmetic or performance coating.
Coatings are everywhere. We paint our walls to change the mood in our rooms. We coat cookware with nonstick substances to keep food from burning. Our clothes have coatings that deflect rain when we're caught out in a shower. And when you consider the number of industrial and medical products that are coated with insulation, sound-deadening material or UV-resistant finishes, you start to realize just how much coatings affect our everyday lives.
These coatings also affect the environment. For example, many coatings that must have some flexibility incorporate petroleum-based polymers like low-density polyethylene (LDPE). And like other oil-based products, these nonbiodegradable substances can fill landfills and sap nonrenewable resources if not properly handled or recycled. Other coatings, such as the anodizing process used to add color and durability to many aluminum products, produce highly toxic chemicals such as sulfuric acid (a contributor to acid rain) and aluminum hydroxide (which can contaminate groundwater if not disposed of properly) [source: Thomas Publishing Company].
But the movement to lessen our collective impact on the planet is affecting coating technology, and the scope of this huge category of materials means that these green changes could significantly reshape humankind's environmental footprint. Some coatings are getting greener than others, and because of the variety of materials that fall into this category, there are a wide range of ways coatings are going green. Read on to learn some of the basics of how coating technology is taking small steps that could have an enormous green impact.
Many Ways to Coat, Many Ways to Go Green
The reduction of environmental damage done by coatings sometimes begins before manufacturing even starts. Research into the carbon footprint of coating materials, or the overall amount of climate-affecting carbon dioxide produced in their manufacture, application, transport and disposal, shows that some coatings simply use fewer resources throughout their life cycles. Coatings such as water-based paints and finishes applied by the powder coating process, in which powdered material is sprayed onto a surface and then baked on to form a tough protective barrier, have lower carbon footprints -- and consequently lower environmental impact -- than coatings that must be thinned with chemical solvents before they are sprayed or painted onto the surface. Simply choosing a lower-impact alternative like these is an instant way to improve the green-ness of a project or product.
Likewise, advances in powder coating have made these finishes tougher, meaning that the new-generation coatings can be applied in thinner layers than their predecessors. Thus, less material gets used in the process; not only does this reduce the amount of overspray -- excess powder that doesn't adhere to the surface and has to be cleaned up afterward -- but it also saves money in situations that involve coating large surfaces, such as the metal sides of shipping containers [source: DSM].
Companies that use or produce coating materials are also going green by changing the processes they use to handle coating-related waste. In anodizing, for example, manufacturers can use chemical flocculants that bind the toxic, waterborne aluminum hydroxide into a solid that can be compacted and handled more easily. They may also employ advanced drying technology to remove most of the water from the sludge created by the flocculent. In some cases, this leftover material contains so much aluminum -- which would otherwise go into a landfill or leach into the environment -- that it can be recycled and used in the production of other aluminum products [source: Thomas Publishing Company].
And recycling plays other roles in helping coatings be more earth friendly. For example, latex house paint (see sidebar) is fairly easy to recycle. Paint recyclers collect the paint, filter it and adjust its pH level to stabilize it for future use. It can be blended with new paint, or may simply be resold as a fully recycled product. Since colored latex paint can accept additional pigment, a can of unused paint could be color-adjusted to match a new project, turning what would once be a can of waste into a money-saving, earth-friendly way to protect and beautify your home. Coatings are indeed a huge part of modern life, but their impact on the world around us is shrinking by the day, thanks to science, creativity and a worldwide commitment to preserving our planet [source: California Department of Resources Recycling and Recovery].