Powder coating and wet coating
What are the advantages and disadvantages of each?
Coil spring coated with powder coating
Compared with wet coatings, the popularity of powder coatings has increased, especially due to their durability, in industrial applications
Surface treatment is essential for the practical use of reactive metals such as ductile iron and carbon steel. If left unprotected, the iron in these metals will react with oxygen to form rust. This means that the colorful appearance is not just decorative, they are also functional barriers to prevent corrosion.
Metal parts can be surface treated with powder paint or wet paint. Although they have similar functions, each coating type has its unique advantages and disadvantages.
Both coatings contain resins, additives and pigments. The main difference is the solvent: Wet paint contains solvent, while powder paint does not.
The solvent in the wet paint keeps all other components in suspension. In contrast, powder coatings are applied in dry powder form. All other differences between powder coatings and wet paints (application methods, color matching, texture, and even operator training requirements) stem from basic differences in chemical composition.
Although applied in different states (liquid and solid), the industrial application methods for powder coatings and liquid coatings are surprisingly similar.
The pretreatment is the same in both processes. Before applying any coating, the surface needs to be thoroughly cleaned. Any oil, dirt, moisture or other contaminants will interfere with surface adhesion.
Apply dry powder to metal parts in powder coating workshop
Powder coating applications rely on negatively charged dry powder being attracted to grounded metal parts
For the powder coating process, the dry powder is shot outside the metal through an electrostatic gun. The spray gun negatively charges the powder, and the negatively charged powder is attracted to the grounded part. Attractiveness leads to quick and even application.
Once the coating reaches the required thickness, the part of the coating is placed in a curing oven, where it is gelled into a powder. Solidification creates hot bonds between the powder particles, resulting in a smooth, hard surface.
Liquid paint is dispensed in a fine spray. It also carries static electricity, but the effect is much worse. Although powder coating can form a uniform coating almost effortlessly and easily, it requires a trained expert to apply the liquid coating to avoid dripping or sagging.
Some liquid paints are air-dried, while others are placed in curing ovens.
It is normal for both powder coatings and liquid coatings to contain primers and colored coatings, but liquid coatings may also include a variety of colored coatings and clear topcoats.
In some applications, the appearance of a completed paint job is almost as important as performance.
Some textures can be obtained very well through powder coatings or wet paints, but certain textures are easier to obtain with specific media.
Powder coatings make it easier to obtain textured finishes. Thinner powder coatings will naturally be more textured, while thicker coatings will be smoother.
Technically, high gloss topcoats can be obtained using powder coatings, but it is much easier to use liquid coatings.
Powder coatings have many advantages, but in terms of color matching, liquid coatings are undoubtedly the winners.
Almost all paint suppliers can mix custom color liquid paints on site with high precision. Blue and red pigments can be mixed to produce purple paint.
In contrast, customized powder coating colors require special production runs. The color of the powder coating depends on the plastic formed by grinding. There is no solvent in the powder coating, so trying to mix blue and red powders will only produce blue and red specks.
Because color matching is difficult, powder coatings are usually produced in a large number of standard colors. Custom orders can be made, but it is more time-consuming and expensive than color matching with wet paint.
Surface treatment is designed to protect metal surfaces from corrosion and other environmental damage. If the finish is damaged due to scratching or chipping, it will no longer act as an effective barrier.
Powder coatings have better performance than wet coatings-because it undergoes thermal bonding during curing and can be applied in thicker layers, it is more resistant to chipping, scratching and other wear. This performance is particularly important for outdoor products such as bollards and bicycle racks.
In addition to physical toughness, powder coatings also have excellent color retention. Long-term exposure to moisture, sunlight and heat will decompose resins in paints and powder coatings.