What Makes the Powder Stick to Wood?

Hopefully by now you have learned a little bit about the powder coating wood process. Here at GCC Coatings, we understand most folks are probably being introduced to and educated about wood powder coating at the same time. Our ultimate aim is to make sure potential customers and clients have a grasp on what it is that we offer and how it can benefit what they do.

With that goal in mind, we will try to answer another common question that people ask when learning about powder coated wood. After getting a general grasp on the process the next question we are usual asked is: So how do you get the powder to stick to the wood?

That is a really good question. A powder finish is very different from liquid paint because it is applied as a solid rather than in liquid form. As a solid, there are no solvents, hazardous air pollutants (HAPs), or volatile organic compounds (VOCs) in the powder. It is safe for people, animals, and the environment; while providing a durable layer of protection to the wood.

Three factors will contribute to getting the powder to stick: the wood, the heat, and charging the powder. Each will be discussed in further detail below.

Picking the Right Wood – This is probably the cornerstone to the entire process. We have very specific criteria that wood boards must meet before we can use it to manufacture parts for powder coating.

After years of research coupled with trial and error, researchers found that medium density fiberboard (MDF) is the best material for powder coating. MDF is an engineered board consisting of various mixed and compressed wood fibers, adhesives, and resins. An MDF board has a surface that is not as porous as other woods and is also uniform.

We know what type of wood needs to be used for powder coating but it does not stop there. The MDF boards still need to meet our established standards before it makes the cut. Part of the process involves rapidly heating and cooling the MDF board. A particular board must have internal bond strength of 130 pounds per square inch in order to withstand that part of our process.

Another important quality of the MDF boards we use is that they have five to seven percent moisture content. That moisture will be used to render the board conductive; something that will make more sense after exploring the other factors below.

Applying the Heat – One of the first parts of the powder coating process is giving the MDF board the ability to conduct an electric current. This is why having a moisture content of five to seven percent in the MDF is important. The board is heated to a very high temperature very quickly in order to draw the moisture to the surface and make it conductive. After being sprayed, the board is again heated so that the powder will gel, flow, and bond to the wood. As it flows the powder wraps around the edges of the part creating a smooth and seamless finish. Because of this, we are able to coat a large variety of irregular and odd shaped parts.

There are currently three types of ovens being used to heat wood surfaces. UV and convection ovens are both options that are being used by various manufacturers to get the wood to the temperature it needs to be at. GCC Coatings uses infrared catalytic ovens for both the preheat and gel portions of the process to heat the surface of the MDF boards. Our infrared ovens are able to get the wood to the optimal temperature for applying the powder without compromising the integrity of the wood. Keep reading to learn why we need the board to be conductive.

Charging the Powder – Finally we arrive to the last factor necessary in getting the powder to stick to the wood. I suppose you could say that this is where the “magic” happens. Once the MDF has been heated and is able to conduct an electrical current it is ready for powder coating.

For an accurate and consistent finish GCC Coatings uses automatic sprayers. Those sprayers are capable of imparting a negative charge to the powder as it is being pushed out of the tip of the sprayer with compressed air. That negative charge makes the powder particles electrostatic; quickly drawing them to the grounded part. (The charge will play a role in helping us reclaim up to 98% of the powder over spray as well.) Another round of heating will cause the powder to permanently bond to the surface of the wood.

It is definitely a very intricate process; requiring all of the necessary parts and pieces to be in place for the best results. Our clients and customers are very pleased with the quality and durability of the powder coated wood parts we manufacture for them. We are capable of handling jobs of all shapes and sizes at our South Beloit, IL manufacturing facilities. Give us a call today for a quote on your next project: (815-624-0288 ext. 11).