Powder coatings, with their environmentally friendly, efficient, and high-performance characteristics, are widely used in various coating scenarios. However, to achieve the best results, strict adherence to the application process and proper storage are essential. Improper application can easily lead to insufficient curing and uneven coating; improper storage can cause powder clumping, deterioration, and even safety risks. This article outlines the core application requirements and safe storage methods for powder coatings, breaking down each key step in easy-to-understand language to help you standardize operations and store safely, ensuring powder coatings remain in optimal condition and achieve stable and satisfactory coating results.

1. Application Requirements

The core application method for powder coatings is electrostatic spraying. The complete process is: surface treatment of the substrate → electrostatic powder coating → melt leveling/crosslinking curing → cooling → finished product. Each step has specific requirements and is indispensable:

1.1 Surface Pretreatment

For a strong and durable coating, surface pretreatment of the substrate is the first and most crucial step. Strictly remove surface impurities such as oil, scale, and rust to ensure a clean, dry, and contaminant-free surface. This step allows the powder coating to bond tightly with the substrate, fully utilizing its anti-corrosion and wear-resistant properties, and extending the coating's lifespan. Inadequate pretreatment can lead to coating peeling and cracking, even with perfect spraying.

1.2 Workpiece Grounding

During spraying, the workpiece must be fully grounded. The core of electrostatic spraying is relying on electrostatic adsorption to attach powder to the workpiece surface. Grounding the workpiece creates a stable electrostatic field, increasing powder spraying efficiency and preventing uneven powder application and waste due to electrostatic repulsion. Poor grounding not only affects the coating effect but can also create electrostatic safety hazards, so it must be taken seriously.

1.3 Defect Repair

If the workpiece surface has large dents, scratches, or other defects, direct spraying will result in uneven coating thickness and a rough surface. In this case, conductive putty should be applied first to fill the surface defects, and the surface should be sanded smooth before spraying. This ensures a smooth and even final coating, improving the product's appearance.

1.4 Curing Control

After spraying, the workpiece must be promptly placed in an oven for curing. Curing conditions must strictly adhere to the technical specifications of the powder coating product—focusing on controlling both curing temperature and time; neither is dispensable. Insufficient temperature or time will result in incomplete curing, leading to poor adhesion, insufficient impact resistance, and other quality issues. Over-curing must also be avoided to prevent a decline in coating performance.

1.5 Immediate Inspection

After powder coating, the workpiece should be inspected immediately to check for uniform coating, missing areas, particles, runs, or other defects. Addressing problems promptly avoids rework after curing, saving costs and improving production efficiency.

1.6 Powder Recovery

During spraying, only a portion of the powder adheres to the workpiece surface. The recovered powder scattered in the spray booth should not be wasted. However, the recovered powder must be screened to remove impurities and clumps before being mixed with new powder in a specific ratio. This reduces costs while ensuring coating effectiveness—note that the mixing ratio must be reasonable to avoid excessive recovered powder affecting coating performance.

1.7 Color Change Cleaning

The powder supply bin, spray booth, and recovery system must be thoroughly cleaned before changing powder colors. Mixing different colored powders can cause contamination, leading to color differences and impurities in the coating, affecting product quality. Therefore, thorough cleaning is essential during color changes.

2. Storage Methods

The storage of powder coatings not only affects the quality of the coating itself but also construction safety. The following seven principles must be strictly followed:

2.1 Temperature and Ventilation Control

The storage area should be well-ventilated, cool, and dry, away from fire sources and direct sunlight. The ambient temperature should be strictly controlled below 35℃. High temperatures can cause the powder to soften and clump, while direct sunlight accelerates powder aging, affecting performance. Insufficient ventilation can easily breed moisture, which also damages powder performance.

2.2 Moisture and Contamination Prevention

Avoid storing powder coatings in damp or leaky places, and keep them away from organic solvents, oils, dust, and other contaminants. Water can cause powder to absorb moisture and clump, and contaminants can mix into the powder, leading to problems such as particles and pinholes after spraying. In severe cases, this can render the entire batch of paint unusable.

2.3 Sealed Storage

Once opened, powder coatings should not be exposed to air. After each use, immediately reseal the packaging or tighten the bag. This prevents moisture, dust, and other impurities from entering, ensuring the purity and flowability of the powder and avoiding issues like powder spillage or uneven application during subsequent uses.

2.4 Safety Precautions

Avoid prolonged direct skin contact when storing and handling powder. If powder adheres to the skin, simply wash it off with soap and water. Do not use solvents to wipe it off—solvents can irritate the skin and pose health risks.

2.5 Equipment Grounding

Coating equipment (such as powder spray guns and coating machines) in the storage area must be properly grounded. Powder is prone to generating static electricity during handling and use; equipment grounding effectively eliminates static electricity buildup and prevents safety accidents caused by static sparks.

2.6 Preventing Discharge

Idle coating machines and other electrical equipment should be properly maintained to prevent unauthorized discharges. Sparks generated by unauthorized discharges may ignite surrounding powder or dust, posing a safety hazard. Therefore, power should be disconnected from idle equipment, and the circuit should be checked regularly for proper functioning.

2.7 Controlling Dust Concentration

If the storage area is adjacent to the powder coating booth, the concentration of airborne dust inside the booth must be strictly controlled and kept below safe levels. Powder dust is flammable; excessively high concentrations may cause an explosion upon contact with an open flame or static spark. Therefore, the powder coating booth must have adequate ventilation, and residual dust should be cleaned promptly.

3. Summary

The application and storage of powder coatings are essentially a dual guarantee of "quality control" and "safety protection": During application, strictly following the seven key steps, including surface treatment, grounding, and curing, ensures a uniform, firm, and performance-compliant coating. During storage, adhering to the seven principles of temperature control, moisture prevention, sealing, and safety protects the powder coating's quality, preventing clumping and deterioration, and eliminating safety risks such as fire and explosion. For manufacturers and operators, these requirements and principles are not complicated; the key is to cultivate good operating and storage habits. Standardized application reduces rework waste, and scientific storage reduces cost losses. Combining both allows the advantages of powder coatings to be fully realized, resulting in superior coating effects. Hopefully, this guide will help you clarify your thinking and make the use of powder coatings more efficient and safer!