The Wild Wild WET

Posted on Thursday, March 19, 2020

It may be cold or even snowing where you are right now, but it’s never too early to start daydreaming about warmer days, is it? A beach stroll, a bike ride, backyard barbecues, and taking the kids to the local water park and splash pad. Chances are you will encounter powder coated products during any of these activities. Yes, even water parks and splash pads use powder coating to protect metal parts from corrosion and the hostile elements.

As a custom powder coater, we often see unique opportunities that present their own set of coating challenges. Last year we were presented with a project that had both strong challenges as well as great opportunity. We were approached by Ashland, OH, based Rain Drop Products, a company that designs and installs custom water parks and splash pads (they call them “spraygrounds”). As we unfortunately hear too often in this business, they were having difficulty receiving high quality, durable, powder coated parts in a timely fashion. A large percentage of Rain Drop Products’ playground fixtures are extremely detailed fiberglass forms and characters they design and coat with liquid paint. While they perform most of the production in-house, they outsource the powder coating process for their metal parts. A project materialized for them which required specific colors and quick turnaround, and they were looking for a reliable custom powder coater. As a PCI 3000 certified company, we felt like we had the processes in place to meet their demands.

We began uncovering the details, and quickly realized the project would require extra planning and thoughtfulness to do it right. Often, size and geometry of parts can present challenges for a project. We have the capability to handle parts as large as 8.5 feet wide by 9.5 feet deep by 30 feet in length, and can hang parts as heavy as 5,000 pounds (depending on the geometry and hole locations on the parts), but in this case the largest part was only about 15 feet long by 6 feet wide and nowhere near our weight capacity. Instead, what made this project so different was the environment where the coatings had to perform. These parts were going to have constant exposure to sunlight in a continually wet environment. Besides that, children were going to be playing on and around these parts every day. However, what we didn’t initially consider was that the water running through the park would be chlorinated to kill bacteria and maintain a safe play area. Not only does chlorine kill bacteria, but it can also highly accelerate corrosion in certain metals. Upon investigation we learned the chlorine and the pH levels of the water impacts the level of corrosivity (a pH level lower than 7.5 creates hypochlorous acid, which, in turn, is a strong oxidizer of iron, for example). We also learned the corrosive behavior of chlorine is common with carbon steel and aluminum (different grades are affected differently), but stainless steel, both 304 and 316, are resistant to chlorinated water corrosion up to a 25mg/L concentration. This project specified 316 steel, so the substrate would be inherently resistant to the chlorine. Rain Drop Products prevents corrosion on the inside of the mostly tubular product by using an insert that isolates the chlorinated water from the stainless steel. But if minor chipping from impact or blistering on the exterior surface occurred, it could quickly become a major coating failure with constant exposure to chlorinated water. Prior to this, we never had to consider chlorinated conditions around our coated products, so we consulted our powder supplier. 

If minor chipping from impact or blistering on the exterior surface occurred, it could quickly become a major coating failure with constant exposure to chlorinated water.

After reviewing the RAL standards and durability requirements for the job with our powder supplier, we concluded we had superdurable polyester powders in our inventory that would meet the demands of the project. However, most of their color selections were bright and pastel colors that could be prone to fading over time in this type of environment, even with the best powder pigment and chemistry systems available. We discussed this possibility with Rain Drop Products, and they were agreeable with our powder selections as long as a zinc-rich epoxy was used, so we began our work. 

As any metal finisher worth their salt spray knows, metal preparation is the foundation of any and all coatings. This becomes even more important with powder coatings that will be subject to harsh, outdoor environments. Using garnet in one of our in-house media blasting rooms, we were able to get a very good white metal blasted surface (SSPC-SP 5) with a 1-1.5 mil blast profile. After a thorough wipe-down and pneumatic cleaning, we had an excellent surface profile on which to apply a robust zinc-rich primer to the 316 stainless steel substrate. We cured the primer to the manufacturer’s recommended cure schedule and then applied the superdurable polyester topcoat and finished it off with the final cure. The project was completed on time and resulted in an attractive, brightly colored, finished product that can withstand kid-tested conditions and Mother Nature’s worst. 

In fact, in follow up conversations with Rain Drop Products, they have told us they occasionally need to remove a small spot of coating to make minor repairs to their splashground equipment, and they have found our coatings extremely difficult to remove. This speaks well of the adhesion we are getting on the substrate compared to what they experienced in the past. We have continued to provide rapid service and high quality, high performance powder coating services for them. We have even started submitting panels to our powder suppliers so they can custom color match powders that are engineered to perform well in water park environments, while matching the liquid colors Rain Drop Products uses on their fiberglass parts. These custom color matching capabilities and formulations will help us continue serving a valued client, helping them continue their mission of building safe, fun, attractive, durable environments for children all over the world. (For more information on Rain Drop Products, visit www.rain-drop.com.)

Terry Watson is sales manager for A Plus Powder Coaters, Inc.