Powder coating and liquid paint are the two primary methods of finishing metal surfaces, such as parts for machines, vehicles, aircraft, appliances, and others. Liquid coating is more widespread now, but powder coating is slowly and steadily gaining its well-deserved recognition. More and more manufacturers are looking into switching from wet paint to dry powder for various reasons.
These reasons range from saving costs, increasing productivity and efficiency, improving workplace safety and protecting the environment, to the undeniable durability of powder coating over conventional liquid coatings.
Is powder coating more durable than liquid paint? What type of durability are we talking about here? We’ll answer these questions and more in this blog post.
Chemistry
To understand the different characteristics of wet paint and powder coating, we need to examine the differences in their chemical compositions.
- Liquid Paint
As its name suggests, liquid paint is in liquid form. It contains resins, additives, and pigments. It also contains solvents that help it stay in its liquid suspension form. Because of this feature, it is easy to mix wet paint colors – everyone knows that combining yellow and blue gives green, blue and red gives purple, etc.
Liquid paint also contains volatile organic compounds (VOCs). Volatile compounds evaporate and spread through the air. They are toxic to the environment and pose a health hazard to operators who work with liquid paint. This is why they must wear protective equipment and masks when working in wet paint application.
- Dry Powder
Powder also contains resins, additives, and pigments. It does not contain solvents because it is in the form of finely ground particles, not liquid. It also doesn’t have any VOCs, making it infinitely safer for the environment and coating workers.
At the same time, it’s not easy to mix and match colors with powder. Yellow and blue powder particles won’t give green powder – they will just provide a speckle of yellow and blue particles. This is one area where liquid paint has an advantage over powder.
Application
Even though these two coating materials are in different states (solid and liquid), their industrial application doesn’t differ too much.
- Liquid Paint
The wet painting consists of shooting the paint through a spray gun at the metal surface. It comes out in a fine spray, and expert handling is required to avoid dripping or sagging of the paint. During liquid coating, it is common to expect plenty of oversprays, as not all of the paint that comes out of the spray gun will adhere to the metal part.
After coating with wet paint, the metal surface is left to air-dry. If the manufacturer wants to speed up the process of drying, they can invest in curing ovens.
Liquid paint may require multiple color coats and a clear topcoat for additional shine or texture.
- Dry Powder
There are two commonly used techniques for powder coating.
One includes a spray gun as well, a special electrostatic one. The electrostatic spray gun charges the powder particles with an electrostatic charge. These charged particles are then drawn to the metal surface, and they adhere to it firmly. In this process, there is little powder coating overspray. But, unlike liquid paint, the excess powder can be recollected and reused.
The other coating method includes a fluidized bed (a tank with a porous bottom) where the powder is suspended. Metal parts are then dipped into this fluidized bed.
Powder coating requires a curing oven. Strong thermal bonds are created between the powder particles during the curing process, giving the product a smooth, durable finish.
Durability
Metal surfaces need to be coated to be of the right color for the overall design and chemical and corrosion resistance and protection against environmental damage such as wind, rain, direct sunlight, etc. If the coating barrier gets damaged in some way, then the metal product not only looks terrible, but it also loses its protection against corrosion and other influences.
Powder-coated surfaces are proven to have a far more durable finish than liquid coated ones. The primary reason for this is the thermal bonding the powder goes through while curing and because it can be applied as a thicker coating. This durability is especially significant for outdoor products, such as bike racks, metal posts, and similar.
Compared to a liquid coat, powder coating is more resistant to scratching, chipping, and other forms of wear. Powder also doesn’t drip or run, forming a more uniform layer of color and protection.
Powder provides superior color retention. When exposed to the elements, such as moisture, heat, or sunlight, the powder, and liquid coatings resins start to break down. This is a process called chalking, which leads to powder particles and resin losing their adhesion properties. The affected particles form a chalk-like layer on the surface.
Early stages of chalking lead to a faded appearance, but severe chalking compromises surface protection and erodes the coating. Powder coats are infinitely more resistant to chalking than wet paint, especially polyester-based powder.
The final result of using a powder coat over liquid paint is a powder-coated product with a durable, high-quality finish that stays fresh and bright for longer.
Other Benefits of Powder Coating
Durability is not the only reason why powder is a better coating option than wet painting. For manufacturers who are debating whether or not to switch to powder from liquid paint, the following benefits should also be taken into account:
- Powder overspray can be reclaimed and used again, minimizing the amount of wasted material.
- Because it doesn’t contain VOCs, the powder is safe for the environment (not an industrial pollutant like wet paint), and it doesn’t cause any health issues for workers who operate in powder coating.
- The powder is not flammable like liquid paint – storing it won’t pose a potential danger of a chemical fire.
- You don’t need highly-trained experts to work in powder coating booths. Pretty much anyone can learn how to perform the powder coating process.
- You can expect to see a drastic decrease in operational costs because there is less wasted material. Less money is spent on worker training, disposing of environmentally hazardous material, and utility costs such as electricity, gas, and water. Reject rates are also lower, meaning your operators won’t have to rework as many parts.
- Moreover, since powder coating doesn’t have to be air-dried or handled delicately after painting, it can proceed directly to the next step in the production process. With a powder, you will finish more parts in one day than you would with liquid.
Conclusion
Powder coating equipment may be a large investment up front, but it will only prove to be an economically sound decision in the long run. With powder coating, your business will experience a reduction in costs for multiple reasons. Your workers will feel more comfortable working in a safer, healthier environment, and your clients will be over the moon with the final results and the durability of their metal coats.
There is no doubt that powder coating is more durable than wet paint. It is more resistant to scratching, chipping, and other forms of wear, and it also won’t fade as quickly as liquid paint. Furthermore, the powder doesn’t run or drip when applied, meaning it can be applied in a more uniform, thicker coating. Now might be the perfect time for you to consider incorporating a powder coating booth into your operations. Contact GAT systems if you have any questions about this process and would like to know more about how powder coating can transform your business for the better.
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