Powder Coating

Protection from the Elements

By Sean Stowell

Powder coating isn?EUR??,,????'???t something that is readily seen or maybe even thought about by the general public when they see outdoor furniture, but it is a key component in the longevity of many outdoor products specified by landscape architects.

According to the Powder Coating Institute, powder coating is a completely dry finishing process used on a wide range of materials and products. Finely ground particles of pigment and resin are electrostatically charged and sprayed onto products to be coated. The parts to be coated are electrically grounded so the charged particles adhere to them until melted and fused into a solid coating in a curing oven.

Powder coating can be used on anything from outdoor furniture to playground equipment.

Innotek Powder Coatings, LLC, located in Big Spring, Tex., has developed a chip-proof PVC-free plastic powder coating called Polyarmor. Polyarmor is a multipurpose thermoplastic industrial finish designed for mechanical performance, high impact resistance and UV protection. The coating can be applied by electrostatic spray or fluid bed dip in thickness ranging from 7 mils to 80 mils. It can be used on outdoor furniture, bike racks, wire products, and playground decking. The coating requires no cure time, comes in melt-blended colors, and is PVC free.

According to Tim Brinner, director of business development at Innotek, being PVC free is a big selling point for this product.

?EUR??,,????'??This is kind of a high-end PVC or plastisol replacement, but not a direct replacement,?EUR??,,????'?? he told LASN. ?EUR??,,????'??You can put this on thinner and get the same properties out of it as you would with PVC or plastisol.?EUR??,,????'??

Powder coating can be applied in a spray or dip application. Parts are pre-heated and then the coating is applied with a spray gun at 8-12 mils thick.

With that said, you may be wondering what exactly a fluidized bed dip or electrostatic deposition is. A fluidized bed dip begins with preheating parts to 400 degrees (adjusting according to part thickness). The parts are then dipped in a fluidized bed of Polyarmor for 4-6 seconds. Excess powder is blown off and if necessary, parts may be post-baked for a short period of time.

For electrostatic deposition, parts are preheated to 400 degrees like in a fluidized bed dip, and Polyarmor is deposited at 8-12 mils thick. Parts can also be post-baked for improved surface finish. It is then coated with the material coming out of a powder gun.

There is no cure time necessary for this system. According to Innotek technical data, thermoplastic powder coatings need only be heated enough to flow out the coating, nothing more. Overheating may cause degradation or embitterment of the coating. Coating may be put into service when cooled.

Thermoplastic powders meet and often exceed the functional properties of plastisol and PVC coatings. Plastisol and PVC coating have been a mainstay in the powder coating business for quite some time, and just now people are beginning to see the advantages of thermoplastic coatings.

Thicker applications of powder coating may be necessary on heavily-built park benches, but landscape architects can specify thinner coatings for finer site amenities, such as light poles and outdoor dining furniture.

?EUR??,,????'??The main difference between what we have Plastisol is that there is no heavy, globby look and no drips,?EUR??,,????'?? Brinner said. ?EUR??,,????'??That heavy look is common in the parks and recreation market. This is a thinner, sleeker look for something that goes on higher end amenities in a downtown cityscape.?EUR??,,????'??

One company using both methods is Webcoat Products located in McAlester, Oklahoma. Webcoat makes a line of site furnishing and according to the company?EUR??,,????'???s owner, Robert Web, plastisol and Polyarmor both have their place.

?EUR??,,????'??The disadvantage of plastisol is that it is a dipped process so one side will always have the drips,?EUR??,,????'?? he said. ?EUR??,,????'??This won?EUR??,,????'???t matter for playground equipment or tables, but when we are talking about streetscapes and site amenities we need a higher quality finish and we go with the Polyarmor.?EUR??,,????'??

Despite its relatively thin finish, this product is very resilient. According to Innotek technical information, the abrasion and impact resistance of this system is proven in the more than 2,000 hours of salt spray testing this product has gone through.

Web said he has used the poly application off and on for about five years, and the product has become stronger over the years to where he now uses it on his finer site furnishings.

?EUR??,,????'??The plastisol looks heavy and industrial, like something you?EUR??,,????'???d throw a keg of beer up on,?EUR??,,????'?? Brinner said. ?EUR??,,????'??We can handle the keg, but our finish looks like it could be in front of a Starbucks.?EUR??,,????'??

For more information visit www.innotekpowdercoatings.com