With the increasingly wide application of powder coatings, users face more and more choices in the market. However, the quality of powder coatings varies significantly. In some cases, users may unintentionally purchase low-quality products. Therefore, it is very important to know how to evaluate and distinguish high-quality powder coatings.
This article introduces several practical methods to help identify the quality of powder coatings.
1. Judging by Coverage Area (Spray Efficiency)
The resin content of powder coatings is typically around 50–60%. However, some low-quality suppliers reduce resin content to 40% or even lower in order to reduce cost and selling price, replacing it with excessive fillers. This leads to a significant reduction in coating coverage.
The quality can be evaluated by comparing the coverage area per kilogram of powder:
Apply different powders to identical products under the same conditions. The powder that covers more area per kilogram is of better quality, while the one with lower coverage is inferior and results in higher application cost.
For example, if 1 kg of powder can normally cover 7 m², every 1 m² reduction in coverage may increase cost by approximately 3–6 RMB per kg. Therefore, when selecting suppliers, coating coverage should be considered as an important evaluation factor, not only the price per kilogram.
2. Judging by Appearance Characteristics of Powder
a. Bulk Volume
Powder with larger volume generally contains less filler and has higher cost and better quality. Powder with smaller volume contains more filler, lower cost, and poorer performance.
For the same 25 kg packaging specification, the larger the volume, the better the powder quality. Small volume powder tends to have poor spraying performance, higher overspray rate, more waste, and lower coverage efficiency.
b. Hand Feel
High-quality powder feels smooth, silky, light, and fluffy when held in hand.
Low-quality powder feels heavy, rough, and compact, with poor fluidity and more overspray loss.
c. Shelf Life
High-quality powder can be stored for a long time without performance degradation. Even after long storage, leveling and other properties remain stable.
Low-quality powder is unstable and deteriorates easily. After about 3 months, leveling and appearance begin to decline. Some poor powders may show accelerated chalking and aging after 6 months.
For example, high-quality products (such as Geelys powder) can be stored normally for up to 12 months at room temperature without deterioration.
3. Operator-Based Spraying Efficiency Evaluation
High-quality powder has excellent transfer efficiency and is easy to spray. Typically, 1–3 spray passes can fully cover the substrate, with minimal overspray and high working efficiency.
Low-quality powder has poor transfer efficiency and requires 3–5 spray passes to achieve full coverage, resulting in more overspray powder, lower productivity, and increased labor burden.
Operators can evaluate quality by observing powder adhesion efficiency, overspray amount, and production output within the same working time.
4. Evaluation by High-Temperature Baking
Set the curing oven temperature to 220–230°C and maintain for 10–15 minutes.
High-quality powder shows excellent heat resistance and weather resistance, with minimal changes in appearance and gloss after curing.
Low-quality powder shows significant changes after baking, including noticeable gloss reduction and dull appearance.
This method is particularly effective for evaluating light-colored outdoor powders.
Smoke Generation During Curing
High-quality powder produces little or no smoke during curing.
Low-quality powder generates a large amount of smoke during the curing process.
Appearance and Gloss After Curing
High-quality powder coatings have a fine, full, transparent, and three-dimensional appearance after curing.
Low-quality coatings appear dull, flat, cloudy, and lack depth.
High-quality powder maintains long-term gloss stability, while low-quality powder may initially appear acceptable but will lose gloss, chalk, or peel after several months.
5. Adhesion and Aging Performance
High-quality powder has strong adhesion and toughness, and can resist chalking and aging for several years.
Low-quality powder has weak adhesion and brittleness, and may begin aging, chalking, or degrading within 3 to 6 months after application.
Comparative tests such as adhesion and bending performance, as well as long-term observation, can effectively determine coating durability.
Poor adhesion and rapid aging will lead to rusting, coating failure, and shortened product lifespan.
6. Compliance and Testing Reports
High-quality powder suppliers can provide valid SGS reports, RoHS reports, and environmental compliance certificates, ensuring product safety and regulatory compliance.
Low-quality materials or recycled powders often cannot guarantee long-term environmental compliance and may exceed regulatory limits.
When selecting powder coatings, a comprehensive evaluation should be conducted, including spray efficiency, curing performance, appearance and gloss, adhesion and aging resistance, as well as environmental compliance, to ensure the selection of high-quality products.
We sincerely welcome your inquiries regarding product performance, industry standards, application methods, precautions, or any related questions.
