The Pros and Cons of Powder and Liquid Coatings

When asked about the differences between powder and liquid coatings, Bill Lemons, Technical Manager at AkzoNobel, outlined the key advantages of powder coatings.  

Powder Coating Advantages  

- Lower VOC Content: Powder coatings generally contain fewer volatile organic compounds (VOCs) compared to most solvent-based liquid coatings. This is because solvents are not needed to keep the paint in suspension, nor are they used to adjust viscosity or modify flow characteristics in the final finish.  

- Higher Film Thickness: Powder coatings typically result in a thicker dry film compared to liquid coatings, which can be applied without issues like runs, drips, or sags. This thicker coating is particularly beneficial in applications where additional durability is needed, such as underbody parts or areas prone to stone chipping.  

- Recyclable Overspray: One of the major benefits of powder coatings is that the overspray can be recycled, leading to improved transfer efficiency and a more cost-effective paint consumption rate.  

- Long-Term Storage Stability: Powder coatings offer excellent long-term storage stability, ensuring that the coating remains in optimal condition until it's ready to be applied.

Powder coating disadvantages

- Specialized electrostatic spray equipment is required for application and the surface must be conductive to accept the charged paint particles. This limits the ability of powder coatings to penetrate well into parts that have deep recesses.

- All powder coatings used in industrial applications must be baked in an oven; ambient curing is not a viable option. Achieving continuous, thin paint films of 1 mil (25 microns) or less is challenging with powder coatings. Additionally, changing colors in a production environment can be slow and cumbersome. Powder coatings also tend to have higher orange peel readings compared to liquid coatings.

- Another limitation is that powder coatings cannot be mixed to create different colors. Unlike liquid paint technologies, which use mixing-machine or toner systems, powder colors must be pre-manufactured to the final color match at the paint supplier’s facility.

Liquid Coating Advantages  

- Low VOC Options: Low VOC liquid coatings are available, making them suitable for use in regulated areas.  

- Lower Film Builds: Liquid coatings can be applied with thinner film builds, reducing the amount of coating required, which can be more economical.  

- Ambient Cure Option: Some liquid paint technologies offer ambient curing, eliminating the need for an oven. This is especially useful in situations where specific parts need to be taped off during repair operations or when creating custom color designs, such as on vehicles.  

- Versatility with Substrates: A wide range of substrates can be painted with conventional liquid coatings, and they do not need to be conductive for most applications. However, substrates must be properly prepared and compatible with the paint for optimal adhesion.  

- Color Flexibility: Liquid coatings offer a broad variety of color options from a single toner mixing bank, making it easy to switch between colors in a production environment.  

Liquid Coating Disadvantages  

- High VOC Content: Many liquid coatings have high VOC levels, which can limit their use in regulated areas.  

- Specialized Training Required: Liquid spray applications require significant training and hands-on experience to achieve competent results.  

- Ventilation and Safety Needs: Spray booths with adequate ventilation are necessary, along with other capital investments, to ensure a controlled, clean, and safe environment. The use and storage of solvent-based paints and flammable solvents also incur high insurance costs.