Thick, tough coating without solvents! Learn about "Powder Coating," ideal for painting frames and complex parts.

Paints applied by brush, can spray, or spray gun are "liquid," and a coating film is formed as the solvent evaporates after painting. In contrast, powder coating, also known as powder coating, is literally a "powder" paint. Here, we will explain why powder paint becomes a coating film and the differences and features of powder coating compared to solvent-based paints.

Microscopic Resin Powder is Electrostatically Charged and Adheres to Metal

While the paints we use for DIY painting, such as brush-on or can spray, are liquid, powder coating is often used for painting metal objects such as storage sheds and racks used in industrial products and homes.

The characteristic of this coating method is that solid paint, micronized into powder, is melted by heating and then hardened without using solvents. By not using solvents, the emission of volatile organic compounds such as thinners is extremely low, and the paint utilization efficiency is high, resulting in low environmental impact and minimal paint loss.

Liquid paints are difficult to apply thickly because the solvent evaporates during the drying process (if applied too thickly at once, it will drip, so time must be allowed between coats). In contrast, powder coating, which does not contain solvents, results in a thick coating film with high adhesion to metal, making it suitable for painting motorcycle frames, swingarms, and cast wheels.

The rear carrier, with its paint peeled off due to age and covered in rust. Powder coating, with its thick and highly adhesive coating film, is ideal for repainting such parts.

A quick touch-up with brush-on paint to hide imperfections will not last long, and rust will surely be exposed within a short period. Therefore, powder coating provides a fundamental solution.

Static electricity is used to adhere the powder paint. Specifically, paint particles are electrostatically charged at high voltage using a dedicated device called a corona gun (electrostatic gun) and sprayed with air. The fine, lightly charged paint particles are then electrostatically attracted to the earthed object to be painted and adhere uniformly.

With liquid paints, whether applied by brush or spray, the paint must be directly transported to the area to be painted. However, with powder coating, the paint adheres due to static electricity, so it adheres to areas that are difficult for brushes or spray guns to reach, such as the underside of springs or frame tubes, "the powder paint adheres to the parts on its own."

This allows for high-quality painting with minimal unevenness, regardless of the operator's skill level.

At Carvek, the contractor, old paint and rust are removed all at once using sandblasting.

Powerful sandblasting removes even deep-seated rust in just a few minutes. Since new rust is likely to form on the exposed base material, it is important to paint as soon as possible.

High-Temperature Baking is Essential to Turn Powder into a Coating Film

Powder paint adhered by static electricity remains powder indefinitely at room temperature and can be easily blown away by rubbing with a finger or blowing air. Therefore, high-temperature heating is essential to turn powder paint into a coating film.

Specifically, it is baked for about one hour in a baking oven at around 200°C. This causes the powder to melt and flow, forming a smooth film, which then hardens into a strong coating. The typical resin components that make up powder coating paints include epoxy, polyester, and epoxy-polyester hybrids, all of which are designed to form a coating film when heated at high temperatures.

Carvek offers nearly 100 colors of powder coatings, including solid base colors, metallics, candies, color clears, and wrinkle finishes, catering to both restoration and custom needs.

Powder paint is literally a fine powder and cannot be applied in this state.

This is where the electrostatic gun for powder coating comes in. This gun generates a high voltage of 100,000 volts by connecting to a household 100V outlet, allowing it to impart a high charge to the powder paint. By connecting a ground wire to the object to be painted, the paint sprayed from the gun adheres to the parts on its own due to static electricity, enabling painting without leaving any areas unpainted, even in places difficult for the electrostatic gun to reach.

As can be seen from the process of adhering with static electricity and then baking at high temperatures, there are restrictions on the materials that can be powder coated:

1. Must be conductive (must be metal parts)
2. Must not degrade at high baking temperatures of around 200°C

Metals such as iron, aluminum, and stainless steel are not a problem, but it is clear that it cannot be used on resin or rubber parts. Also, it is important that the temperature of the entire part rises from the core during baking, making a baking oven an essential item.

You might think that a heat gun could be used to heat small parts, but powder paint is easily scattered by the hot air from a heat gun. Furthermore, even if the surface of the paint is heated, the part's temperature must rise for adhesion to occur.

The high initial investment in equipment such as corona guns and baking ovens is a significant hurdle for DIY enthusiasts.

Baking is a crucial step essential for powder coating. By baking at 190°C for 20 minutes, after considering the time for the part itself to reach temperature, the paint exhibits its full performance.

Carvek also develops ovens for baked paints, including powder coatings, GunKote, and acrylic paints. This oven has an internal width of 1800mm, allowing for the baking of motorcycle frames.

Powder Coating Excels in Durability and Environmental Performance

While powder coating is difficult to do as a DIY project, it offers various advantages and features when commissioned to a professional.

The biggest feature is its "tough and highly durable coating film." Powder coating frames and wheels, which are subjected to impacts from gravel and small stones kicked up by tires, can prevent problems such as scratches and peeling of the coating film. As mentioned earlier, powder paint adheres with a thicker film than liquid paint, providing superior impact resistance.

Furthermore, powder paint, which adheres through static electricity, results in fewer missed spots even on parts with complex shapes, and its excellent rust prevention capabilities are also a strength. The thick coating film also contributes to rust prevention.

The rear carrier, beautifully finished after baking at 190°C for one hour, considering the time for the part itself to reach temperature. It is a valuable asset for full restorations and can also be used for repainting individual parts.

The HOTROD Black has a characteristic fine, textured finish. In addition to its unique appearance, it also has the advantage of providing a non-slip grip. Powder coating is highly durable, making it ideal for painting carriers where luggage is tied down.

The fact that it is "less prone to uneven coating" is also noteworthy. When painting complex parts like frames and springs with can spray or spray guns, the common practice is to paint the undersides and shadowed areas first, as they are harder to reach. However, even then, depending on the operator's skill, there can be variations in coating thickness, resulting in unevenness.

In contrast, with powder coating, the electrostatically charged powder paint is attracted to areas where electricity flows easily, allowing for uniform coating even without directly facing the electrostatic gun towards the painted area. In other words, high-quality painting can be achieved without relying on the operator's technique.

However, powder coating is not a universal solution. Firstly, due to the high-temperature baking process, it cannot be used on resin cowls or fenders. Powder paints are generally not designed for color matching through tinting, and the coating film is thick, so they are somewhat inferior to solvent-based paints in terms of flexibility for exterior parts repair and custom painting.

Nevertheless, it is certain that powder coating has advantages for painting frames, stands, wheels, suspension parts, and carriers. Therefore, when repainting these parts, we recommend considering commissioning a professional powder coating specialist.

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