Powder Coating Wood – A Complete Guide
Powder coating has a variety of benefits compared to liquid coating which you can learn about here. One limitation that use to exist was being able to powder coat wood which use to be primarily due to temperature requirements that powder coating is cured at but advances in powder coating has helped to eliminate that problem. Now powder coating can be used with a variety of wood products including MDF, HDF, oak, and ash. This guide will cover critical things to consider when powder coating wood products.
Factor 1 for Powder Coating Wood Products – Powder Type
One of the most important challenges when considering powder coating wood products is that you cannot elevate wood e temperatures to much without risking harm to the wood. For a long time this was the issue that limited the ability to powder coat a wood product. However, there are now low cure powder coatings that will cure at 250 degrees or less. With these types of powders you do not have to raise temperature during curing as much which can reduce the risk of harming the core of the wood board as well as be easier to work with. If a low temp cure powder will not work well other options include those that are cured
Another aspect of powder coating wood to think about is whether you will need a primer prior to a top coat for your wood. Primer helps with three wood powder coating challenges. First it can help hide imperfections in the wood substrate, second it can help promote better adhesion of a powder top coat, and third if moisture content is above 10% it can help lock in moisture to prevent outgassing during curing of the powder coating. While there are one step powders for wood if you want to ensure a smooth finish and maximum adhesion a primer can make sense.
Factor 2 for Powder Coating Wood Products – Powder Application
Powder coating is electrostatically charged and then applied to a grounded part. For a part to ground properly it has to be able to conduct electricity to ground causing it to become electrically neutral. Wood itself is not naturally conductive. However wood can have moisture that builds up within it, which can be electrically conductive. To ensure you will be able to successfully apply powder to your wood product you will want to test to see if you can ground the product with a proper ground detector. If the part shows that it is truly grounded then you should be able to apply powder. However if the part does not register as grounded after applying a grounding cable to the part you will have to enhance the conductivity of the wood to allow it to properly ground. Typically moisture content of 5-7 percent is ideal where if you have to high of moisture this can create issues during cure and to low issues with conductivity. If your part is not grounding due to conductivity you can try a liquid conductivity enhancer which is applied to help improve the boards conductivity.
Thermoplastic powders will typically be applied at a temperature 18 – 36 degrees farenheit below the pre heat oven temperature which will require proper spacing of your powder coating booth and pre heat oven to allow the wood surface to cool down.
Factor 3 for Powder Coating Wood Products – Pre heating & Handling Moisture
Excessive moisture can create outgassing when you go to cure a powder coated wood product. Additionally certain powders require a surface to be a certain temperature to be able to properly set, these are called thermoplastic powders and usually the surface has to be the exact temperature that the powder melts at.
To address issues with outgassing preheated temperatures you will typically need to consider a convection, UV, or Infrared oven as this will allow for heating of the product to the desired temperature. The right type of oven will require consideration of the powder you plan to use, the product you will be powder coating, and more. Typically for wood powder coating the wood is heated to 212 to 266 degrees Fahrenheit for 5 to 15 minutes.
Factor 4 for Powder Coating Wood – Wood Characteristics
The wood you plan on powder coating has to have a variety of characteristics to be able to be powder coated. The wood has to have a certain porosity and be of certain quality standards. High grade MDF boards are the most suitable but their can be other types of wood that will work with powder coating. You also want to address the wood by properly sanding and if necessary raising the grain prior to powder coating so that you get the desired finish you need.
Factor 5 for Powder Coating Wood – Curing
Once you have prepped and preheated plus applied powder to your wood product the final phase is curing of the powder coating. To cure powder on a wood product you will typically use an infrared, convection, or combination oven (though a UV oven is also an option). Typical cure times range from 5 to 10 minutes and temperatures between 280 and 330. Curing is critical to create a barrier for the wood from moisture.
Ultimately powder coating wood is possible but with the current status of technology there are some limitations. Specifically, powder coating will only work with certain wood and requires special considerations to address moisture as well as curing. By addressing these problems you can ensure that the finish you achieve is high quality in appearance and durability.