In powder coating applications, overall surface quality often reaches the targeted standards; however, the areas that truly determine the long-term performance of a product are the edges. Edge Coverage—the film thickness formed on edges—is one of the most important criteria for evaluating the real durability of a coating. This performance difference becomes especially noticeable in metal parts used outdoors.
The main reason edges tend to form lower film thickness is the behavior of the electrostatic field. While powder particles accumulate easily on flat surfaces, the change in electric field intensity around sharp edges causes natural thinning in these areas. Over time, this thinning can increase the risk of corrosion, weaken UV and chemical resistance, and shorten the overall lifespan of the coating.
At this point, the Faraday cage effect comes into play. In complex or recessed geometries, electric field lines cannot adequately penetrate into the interior of the part; powder particles instead migrate toward outer surfaces where field intensity is higher. This Faraday Cage Effect makes it difficult for paint to accumulate properly in box profile inner corners, indentations, deep channels, and narrow sections. The same principle applies to sharp edges: when the electric field distribution is not ideal, the film formation at the edges is insufficient. Therefore, Edge Coverage performance is closely linked not only to the geometry of the material but also to proper electrostatic field control.
For this reason, understanding why Edge Coverage is critical in production processes is essential. The thickness obtained on the edges directly affects not only aesthetics but also the functional durability of the product.
Key Factors Affecting Edge Coverage
- Formulation
The special formulation chemistry, particle size distribution, and flow characteristics of the powder coating determine how uniformly it spreads toward the edges. At the same time, special flow modifiers and additive systems play a significant role in improving penetration in areas where the Faraday effect creates challenges. - Application conditions
Gun distance, angle, voltage settings, grounding quality, and powder output directly influence film thickness on edge regions. Voltage level, in particular, is a critical parameter in reducing the Faraday cage effect. High voltage can intensify the electric field in narrow areas, making it even harder for powder to reach inner corners; proper voltage management, on the other hand, significantly improves edge coverage performance. - Curing process
If curing is not carried out at the recommended time and temperature, the flow does not complete properly, leading to a weaker film—especially on edges.
When these three factors are evaluated together, it becomes clear that edge coverage performance is both an indicator of product quality and a reflection of disciplined application practices.
Products where edges are critical typically operate under harsh conditions. Exterior façade profiles, lighting fixtures, machinery components, metal furniture, and similar items are exposed to high UV, humidity, temperature changes, and mechanical stress. In such environments, products with poor edge coverage deteriorate more quickly and require more frequent maintenance—resulting in increased operating costs.
At BPC Powder Coatings, we consider edge coverage performance an integral part of our product development process. Our formulations are optimized to achieve a balanced film structure on both flat surfaces and challenging geometries—including areas where the Faraday cage effect is most pronounced, such as inner corners, deep profiles, and complex surfaces. Additionally, products undergo tests simulating real-life conditions to identify and improve potential weaknesses on edge regions.
Core Focus Areas of BPC’s Edge Coverage Approach
- Balanced particle size distribution
• Formulation that support edge flow
• Additive packages tested on challenging geometries and regions affected by the Faraday effect
• Product designs that increase application tolerance
This approach ensures not only visual consistency but also long-term durability and performance.
In conclusion, Edge Coverage is a parameter that can lead to serious quality issues if overlooked in powder coating applications. The film thickness obtained on edges is one of the key factors determining the actual service life of the product. When the right product, correct application, and proper curing come together, it is possible to achieve a reliable and long-lasting coating even on difficult geometries and areas where the Faraday cage effect is strongest.
At BPC Powder Coatings, we treat Edge Coverage performance as a fundamental quality indicator throughout our entire development process. We optimize our formulations to achieve more consistent film build on edges and reinforce them with systems that address weaknesses caused by the Faraday effect. We continuously validate durability through tests conducted on complex geometries.
In short, at BPC, we secure coating performance at the most critical points—on the edges and in all areas influenced by the Faraday effect.
