Powder coating can provide an efficient means of protecting surfaces against mechanical stress and chemical exposure – including cleaning agents and disinfectants that threaten wood products. Unfortunately, powder coating offers an efficient defense against these threats.
MDF boards are an excellent material to work with when it comes to powder coating thanks to their uniform density profile and moisture content, making preheat and coating much simpler allowing for quick production times.
Moisture Content
MDF (Medium Density Fiberboard) is an engineered wood product composed of softwood or hardwood fibers bonded with synthetic resin under heat and pressure, typically found in kitchen and bathroom cabinetry, ready-to-assemble furniture manufacturing, as well as office furniture production due to its design versatility, durability, chemical stain resistance, and chemical resistance.
Powder coating is a low-temperature finishing process with outstanding physical performance capabilities and beautiful aesthetics for non-metal substrates such as MDF and natural or engineered woods. Achieve high-quality results on these temperature sensitive materials requires specific knowledge, equipment, and using premium quality MDF and powders.
MDF must be heated before electrostatic powder coating to aid grounding during electrostatic application of powder coat and to control outgassing, while moisture control prevents drying-out that would disrupt deposition and adhesion of powder coating.
Preparation
Powder coating has long been used on metal, but recently only became possible for MDF due to technological advancements that allow high temperature processes necessary for turning powder into gel and flowing it over the surface without melting it.
These advancements include advances in resin chemistry, UV LED curing lamp technology and a combination preheat/cure oven that utilizes both electric infrared (IR) and gas catalytic IR technologies. Furthermore, leading MDF powder coaters offer in-house cutting and sanding to help control moisture content and ensure quality work.
Powder-coated surfaces offer more resistance than thermoset surfaces to damage, abrasion and chemicals such as alcohol and disinfectant cleaners, helping extend furniture lifespan, which is particularly important when applied commercially such as restaurant tables.
Preheat
Powder coating has long been utilized on metal components, while wood requires more comprehensive preheating processes than metal surfaces.
Once MDF is sanded, it enters a hybrid electric IR/gas convection preheat oven. This process brings core moisture from within to the surface of the MDF board and makes it more conducive for electrostatic charging with powder guns.
This process is essential to prevent outgassing that may cause pinholes in the final coating and ensure a uniform finish. MDF must also be cured at lower temperatures than traditional metal parts to avoid warping and cracking of panel integrity – an advantage provided by UV curing systems instead of thermoset curing systems which require high temperatures for curing.
Gel
MDF (medium density fibreboard, or MDF) is an engineered wood product composed of sawdust, dried wood shavings and biners that is fused together using heat and pressure, creating flat hard boards without knots or splinters that make cutting and working with it much simpler than solid wood or plywood.
MDF does have some disadvantages, however. Through an off-gassing process it can release formaldehyde into the atmosphere, potentially leading to irritation of nose, eyes and throat – particularly a concern for carpenters working daily with it.
Homeowners can reduce this risk by choosing glues with no added formaldehyde and working with MDF outdoors or in an area with good ventilation, and by limiting its exposure to moisture which could cause it to expand and weaken over time.
Curing
Powder coating is most frequently employed on metal substrates that can withstand high temperatures and are conductive; its particles adhere electrostatically.
Unfortunately, wood doesn’t fare so well and cannot tolerate extreme temperatures.
One of the key factors in board density is uniformity – ensuring even preheating, coating and curing processes.
Moisture content of boards is another critical variable; an ideal moisture level when entering the preheat oven should range between 7-9 percent. Preheating drives the core board moisture to the surface, making it conducive for powder guns to use and also reducing outgassing during final cure stages – both factors being crucial to quality and aesthetics.