Issue link: https://www.e-digitaleditions.com/i/1040345
Coater's Corner As powder coaters, we often work hard to dis- tinguish ourselves from the world of liquid coat- ings. We all know the advantages that powder has over liquid. Our environmentally sustainable, low- er-applied-cost, more-durable coat- ing system works well when applied properly and will outlast most com- monly used liquid systems. That is, until it gets damaged in the field – then we have a problem. is is where we as powder coaters need to develop an understanding and appreciation for how liquid coatings can support powder coatings that are already in use. A common misconception "ere is no way to touch up powder coating in the field." When out working to build up our cli- ent base, we often hear the above state- ment as a complaint and reason not to use powder coating on a project. While it is true that you cannot bring an oven to the job site and reapply powder, you can still touch up a damaged coating with a liquid system. is is an oppor- tunity for the custom coater to educate and improve their standing with their prospective customer. Photo 1 shows a fusion bonded epoxy (FBE) panel that has been primed with self-etching epoxy primer and top coat- ed in a liquid two-part urethane. After allowing the proper time for the two- coat system to cure, a pull off adhesion test was done, demonstrating that the liquid coat held on at up to 938 psi. For most applications, this result is more than sufficient. Furthermore, the fail- ure that resulted was not in the FBE base coat but instead was between the self-etching epoxy primer and two-part urethane top coat. erefore, you can touch up powder coating with liquid in the field. The success of the touch up will depend on the following: • Quality of liquid touch-up paint used • Quality of surface preparation prior to coating application • Ability of person doing touch up in the field Quality of the liquid system e most obvious require- ment of the touch-up paint is going to be the color. This is also typically the easiest obstacle to overcome. Most liquid paint suppliers are able to provide a custom color match when you supply them with a powder coated sample panel. I recom- mend providing a physical sample every time instead of submitting a RAL code or an email with a photo. In both cases, there will likely be color variation between what you have sprayed and what is on a sample chart or computer screen. is is an important point as it is a very bad idea to match to a comput- er screen for the following reasons: • Ambient lighting when photo was taken • Quality of camera • Difference in representation of color on customer's com- puter screen vs. your screen • Color samples vary from printer to printer When done properly, you should see results in gloss and color accuracy, as represented in Photo 2. This photo shows a two-part urethane match to a super-durable polyester powder top coat. Chris McKinnon Aegis Industrial Finishing Powder coating touch ups in the field? Yes, we can! POWDER COATING, October 2018 35 Photo 1