More electronics producers are moving to magnesium to make cell phones and laptop computers lighter and more durable. Often, powder coating is providing a high-end finish that contributes to the external durability of the device. Applied Coating Technology, Inc., a custom coater in Minneapolis, Minnesota, U.S., sees magnesium’s use expanding to devices needing durability in the field, such as bar-code readers for parcel delivery. ACT’s first partner in a magnesium application was Itonics, Inc., in Seattle, Washington, U.S., which makes laptop computers that are used on the road in service applications.
“Itonics makes a water-tight laptop that the technician can throw on the front seat of his van, and that will fall off the seat onto the floor,” says Mike Meagher, ACT’s vice president of manufacturing and engineering. The laptop is fitted with a rubber armored boot to absorb impact and it relies on the powder coating of its magnesium shell for abrasion resistance.
“Magnesium presents a lot of problems in getting cleaned and prepped,” Meagher says. One is de-gassing the porous magnesium to prevent the coating from trapping pockets of air and driving them out during the curing process, creating disruptions in the finish. “You can’t just clean the magnesium. It doesn’t lend itself to traditional prepping.”
ACT devised a novel pretreatment process for magnesium that did not produce the “smut” on the surface of the magnesium. The process included: alkaline cleaning, followed by water rinsing, then organo-metallic composite coating, and another water rinse. A specially formulated conversion coating was also key. The product was designed for use as a reactive (rinsable) coating for reactive substrates.
Eliminating smut and achieving powder adhesion created a successful powder coating application.

Thanks to the Powder Coating Institute for providing this information. http://www.powdercoating.org