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Powder coating is a new type of solvent-free, 100% solid powder coating, mainly divided into two categories: thermoplastic and thermosetting. It is made from special resins, pigments, and curing agents through processes such as hot melting, crushing, and sieving. It is stable at room temperature. After electrostatic spraying or fluidized bed dipping followed by heating and baking, a smooth, glossy, permanent coating film is formed, combining decorative and corrosion-resistant properties.
Compared to traditional coatings, its "highlights" are significant:
Super Environmentally Friendly: Solvent-free, non-toxic, and free of volatile organic compounds, it fundamentally avoids the risks of poisoning and fire, and there is no emission of "three wastes" (waste gas, wastewater, and solid waste), perfectly meeting environmental regulations.
Cost-Effective: Overspray powder recovery rate exceeds 99%, maximizing raw material utilization; and sufficient film thickness can be achieved in a single application after pretreatment, eliminating the need for a primer. Automated operation further improves production efficiency.
High Performance: The coating is dense, with excellent adhesion and impact resistance, high edge coverage, and excellent resistance to chemical corrosion and electrical insulation.
Easy Storage and Transportation: Safe and convenient storage and transportation without concerns about solvent leakage.
The principle of electrostatic powder coating is ingenious: the spray gun is connected to a high-voltage negative electrode, and the workpiece is grounded as a positive electrode, creating a strong electrostatic field between them. When compressed air delivers powder to the spray gun, the powder acquires a negative charge and adheres evenly to the workpiece surface under the action of electrostatic force and airflow. After heating and curing, a durable coating film is formed.
The complete process is: surface pretreatment → drying and dehydration → spraying → initial inspection → baking and curing → final inspection → finished product. Specific construction should pay attention to these two scenarios:
To achieve good coating results and a long lifespan, don't overlook these details: Proper pretreatment: Careful surface treatment of the workpiece before spraying is fundamental to maximizing powder performance and extending film life.
Spraying Grounding:The workpiece must be fully grounded to significantly improve powder adsorption efficiency.
Defect Repair: For workpieces with large surface defects, apply conductive putty first to ensure a smooth and even coating.
Standardized Curing: After spraying, control the curing temperature and time according to the powder coating specifications. Insufficient curing can easily lead to quality problems.
Timely Inspection: Inspect immediately after spraying. Minor defects can be handled on-site. After curing, if defects are small and do not affect the finish, they can be repaired with a diluted powder of the same color and acetone. Large defects require sanding, respraying, or paint removal and rework.
Recycled Powder Reuse: Recycled powder must be screened to remove impurities before being mixed with new powder in the correct proportions.
Preventing Color Cross-Contamination: Avoid color mixing in the powder supply, spraying, and recycling systems. Thoroughly clean the system before changing colors.
Artistic powder coatings can create high-quality, three-dimensional patterns, but their application has a lower tolerance for error:
Control Parameters: The spraying air pressure should not be too high (0.5-1.5 kg/cm² is optimal). Excessive air pressure will cause the pattern to become blurred and develop pits. The electrostatic voltage should also be moderate (around 60-70 kV). High voltage can cause powder rebound, resulting in pitting and poor leveling.
Sufficient Film Thickness:The recommended film thickness is 70-100 μm. Too thin a film will result in indistinct patterns and may expose the substrate.
Precise Curing: Baking must be strictly performed according to the specified temperature and time. Low temperature/short time will not only prevent the pattern from developing but also compromise the mechanical properties of the coating. Furthermore, reusing recycled artistic powder will cause the pattern to become smaller/lighter; it is recommended to avoid this method if possible, and conduct a trial beforehand.
Storage environment should be "fireproof, lightproof, and well-ventilated," with a temperature not exceeding 35℃.
Keep away from water, organic solvents, oil, and other contaminants to prevent coating deterioration.
Seal the packaging immediately after use to prevent powder exposure to air and contamination by foreign matter.
Avoid prolonged skin contact. If skin contact occurs, wash with soap and water; do not use solvents.
Spraying equipment must be properly grounded to eliminate static electricity hazards.
Prevent unauthorized discharge from the equipment.
The concentration of suspended dust in the powder spraying chamber must be controlled below safe levels to prevent dust ignition and explosion.
Powder coatings are an environmentally friendly, efficient, and high-performance coating option. From surface treatment before application to parameter control and curing details during spraying, and storage and site safety, every detail affects the final result. By accurately controlling these key points, both general-purpose and artistic powders can achieve ideal coating effects; at the same time, proper storage and safety management can make construction easier and more reliable.
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