Powder coatings, a tough, effective and sustainable alternative to traditional liquid coatings

Powder coatings, an innovation redefining the aesthetics and functionality of wood finishes

In an era where sustainability and innovation go hand in hand, finishing wood with powder coatings represents a significant step forward in the woodworking industry. Traditionally, liquid paints have dominated the finishing landscape due to their ease of application and wide range of colors. However, concerns about ecological impact and paint efficiency have led to the search for more environmentally friendly alternatives. Powder coatings, mainly known in metal finishing, now offer an outstanding solution for wood as well, due to their significant advantages in terms of durability, efficiency and sustainability.

Finishing wood with powder coatings is not only a technological innovation, but also a redefinition of aesthetics and functionality in the wood industry. This method promises to bring a transformation in the way we view the durability and beauty of wood finishes, while offering an environmentally friendly alternative to traditional painting methods.

Particularities of finishing wood with powder coatings

Since the 1960s, advanced technologies using powder coatings have provided household appliances, automotive parts, sports goods and other metal objects with a tough, durable, aesthetic and much more environmentally friendly finish. They relied on the electrical conductivity of the metal and its resistance to the high temperatures at which powder coatings were transformed into a tough, adherent finish. The advantages of these technologies led to a desire to use them for finishing other materials. The extension to the finishing of wood and its derivatives was, however, hampered by the important differences between metal and wood:

• Metal is a good conductor of electricity, while wood is an insulator
• Metal has a uniform structure and smooth surface, wood is uneven and porous
• At high temperatures water tends to seep out of wood, metal does not have this problem

The formulation of powder paints with low and very low melting and polymerization temperatures paved the way for their use for wood. Initially they were used only for MDF panels, much more uniform in structure and with a less porous surface. Gradually, technologies were developed that could also coat different types of denser and more stable hardwood.

The powder coating process involves three important elements - the wood substrate, temperature and electrical charge. Support it should be a good conductor of electricity, have as smooth a surface as possible, and have a moisture content in the range 5-7%. Temperature is important because when applied on metal, the reaction is finalized at over 120°C. The new powder coatings developed specifically for wood need 90°C and even less, reacting in a very short time to avoid water out. Electrical charging was solved by preheating the wood for a short time. Preheating brings water to the surface and turns wood from an insulating material into a good conductor of electricity.

How to cover wood with powder paints

Coating wood and wood derivatives with powder coatings is no longer a novelty. We use it for both MDF and wood. One of the company's lines Plimob, the Sighetu Marmației-based manufacturer of wooden chairs and IKEA's largest supplier of such products, uses powder paints to finish the seats. Each factory using this method has its own technology adapted to the type of material to be coated.

To achieve a quality coating, surfaces need to be well sanded and cleaned of dust and conductivity. Sometimes the moisture content in the wood is sufficient and constant to provide the necessary conductivity and it can be coated directly. Other times a pre-treatment, by spraying, with a solution that increases the surface conductivity is needed. For finishing, parts are preheated to the coating temperature set by the technology to partially melt the powder, making it liquid. In this state the paint flows when applied and thus adheres better to the part. The uniform surface temperature of the part allows high transfer efficiency and a continuous film appearance.

The paint cures after application on wood or MDF due to a chemical reaction that takes place at temperature or in UV. Thermally cured paints end up in infrared (IR) ovens, convection ovens or hybrid ovens that combine the two processes. UV-cured paints need minimal heat to cure, and the process is completed in seconds. Before that, however, they need to be heated in an infrared or convection oven to become liquid, which can take 2-10 minutes. Finally, the pieces are cooled naturally or in a cooling tunnel.

Benefits of powder coating wood

Powder coating wood and MDF offers a number of significant advantages. These include:

• Improved grip. The powder adheres firmly to the surface of the wood, ensuring a strong and durable adhesion.
• Chemical, mechanical and scratch resistance. The chemical- and scratch-resistant finish keeps the look of the object unchanged for the long term.
• Sustainability. Powder coating gives the wood additional protection against wear and environmental factors.
• Cost efficiency. The powder coating process can reduce production costs by requiring fewer coats, sanding and mechanical preparation.
• Modern and eco-friendly look. The powder finish has a state-of-the-art look and helps reduce volatile organic compound (VOC) emissions.
• Easy maintenance. The powder-coated surface is easy to clean and maintain, keeping its original appearance for a long time.

Although there are some challenges associated with the powder coating process, such as retouching and controlling the drying process, the obvious benefits and evolving technology make powder coating an attractive option for finishing wood and MDF.

Misconceptions about finishing wood with powder coatings

Although, as I said, powder coating of wood and MDF has been done industrially for many years, there are still misconceptions about the technology. Here are some of them:

Not as durable as other finishes. In fact, powder applied to MDF and wood gives a very durable finish that is resistant to abrasion, stains and impact. What's more, there are no peeling or cracking as with laminate products.

You need large series to be profitable. The powder coating process is flexible and can be efficient even for small batch production.

There is a limited range of colors and gloss levels. The manufacturers that make such coatings demonstrate that there is a wide variety of colors and gloss levels available, and it is even possible to customize to customers' needs.

Powder coating wood is very simple and within everyone's reach. The process requires appropriate technology and equipment. It also needs experience and skills to implement it correctly. It is different and more complicated than powder coating of metals.

It's just a cheap finish for wood. Initially, when technologies were still in their infancy, there were also products whose quality left something to be desired. But now, after years of use, powder-coated wood has a high quality, durable and aesthetic finish.

Conclusion

Wood finishing with powder coatings represents a revolution in woodworking, offering a sustainable, durable and aesthetically pleasing alternative to traditional finishing methods. The differences with metal painting underline the adaptability and versatility of this technology, opening new horizons for innovation in the design and production of furniture and other wood products. As the technology continues to evolve, it is expected that wood finishing with powder coatings will become increasingly popular, setting new standards of quality and sustainability in the industry.

I hope you find the above information useful. As always, additions are welcome. And if you have any questions or clarifications, leave them in the dedicated space. I'll be sure to reply.