How to Identify the Quality of Powder Coatings

I. Visual Inspection Methods:

Good quality powder should feel smooth, lightweight, and airy when touched. In contrast, poor-quality powder feels rough and heavy. When you hold a handful of powder, the smoother and lighter it feels, the better the quality. Conversely, rough and heavy-feeling powder indicates lower quality. Poor-quality powder is challenging to apply, leading to significant powder wastage.

Larger powder volumes contain fewer filler materials, resulting in higher quality and cost. Smaller volumes contain more filler materials, leading to lower quality and reduced cost. When comparing powders of the same weight, a larger volume indicates better quality, while a smaller volume suggests lower quality. Lower-quality powders are less efficient to apply, leading to increased powder wastage and higher usage costs.

High-quality powder coatings can be stored for an extended period without significant changes in flow and other characteristics. In contrast, lower-quality powders may deteriorate in as little as three months, resulting in reduced flow and leveling properties. Standard room-temperature powders typically have a shelf life of 12 months, while those made with lower-quality raw materials are more prone to instability and potential issues. Using low-quality raw materials can accelerate the aging and deterioration of powder coatings within six months. Moreover, poor-quality powders are challenging to store, leading to substantial powder wastage and increased costs.

II. Coating Area:

The resin content in a standard powder coating should be around 55-65%, with resin prices averaging around 20 yuan/KG and fillers at about 2 yuan/KG. Some subpar powder manufacturers use resin contents below 45% to cut costs and increase filler content to reduce costs and coating area. By comparing coatings from two companies using the same powder to coat the same product, you can easily see the differences in the coating areas. More coating indicates a higher-quality product with lower usage costs.

III. Powder Transfer Efficiency:

Powders with good fill rates are easier to apply, requiring only 1-3 sprays to cover the substrate. This results in less powder wastage and higher efficiency. Poor-quality powders are more challenging to spray, typically requiring 3-5 sprays to achieve coverage, leading to higher powder wastage and reduced efficiency. Operators can use the powder application rate to determine if there is significant powder loss. Producing fewer products and recovering more powder increases the workload for operators, leading to reduced efficiency.

IV. Baking Test:

Good-quality powders produce minimal smoke during the baking process, while lower-quality powders produce a significant amount of smoke.

V. Appearance and Gloss After Baking:

High-quality powders create coatings with a refined, full, transparent, and three-dimensional appearance that retains its relative gloss over time. In contrast, lower-quality powders result in coatings that appear dull, lack luster, become hazy, and lack transparency. The gloss may initially be good, but it doesn't maintain its shine over time, leading to loss of gloss, powder flaking, and peeling after a period.

VI. Adhesion and Aging:

Good-quality powders exhibit strong adhesion, resilience, and resistance to powdering and aging over several years. Poor-quality powders, on the other hand, have weak adhesion, are brittle, and begin to powder and age after just a few months. To test adhesion and flexibility, you can observe whether the product ages or powders a few months after application. Weak adhesion results in products that are prone to aging, powdering, rusting, and shortened lifespans.

VII. High-Temperature Test:

By heating the powder to 220-230 degrees Celsius and maintaining it for 10-15 minutes, you can assess its heat resistance. Good-quality powders are highly resistant to heat and weathering, experiencing minimal color and gloss changes after high-temperature baking. In contrast, poor-quality powders are less heat and weather resistant, exhibiting significant color changes and a dull appearance after high-temperature exposure. This method is particularly effective in testing light-colored outdoor powders. Low-quality powders, which use subpar resins, titanium dioxide, and cheap color fillers, have poor heat and weather resistance. These powders have lower costs but lower quality.