Picture frame effect in powder coating: causes, solutions & practical tips

The picture frame effect is a common phenomenon in powder coating, where visible lines or shadows form on the edges or borders of workpieces. This undesirable pattern can significantly impair the appearance and quality of the coating.

Causes of the picture frame effect

• Uneven powder distribution: Higher powder deposits can occur at edges and corners, resulting in visible lines.
• Electrostatic charging: Different charges at different points on the workpiece can lead to uneven powder adhesion.
• Unsuitable application techniques: Incorrect spray gun distances or angles can intensify the effect.

Measures to prevent

• Optimise the application technique: Ensure even movements and correct distances during the coating process.
• Use suitable guns: Using guns with even powder output can help to minimise the effect.
• Adjust voltage settings: Reducing the high voltage can reduce powder deposition on edges.

Practical example: Use of the SuperCorona® ring

Gema offers the SuperCorona® ring as a solution for reducing the picture frame effect. Its special design ensures more even powder distribution, especially in critical areas such as edges and corners. Further information can be found on the official Gema website.

Conclusion

The picture frame effect is a challenge in powder coating, but it can be effectively avoided through targeted measures and the use of suitable technologies. Continuous monitoring and adjustment of the coating process is crucial for optimal results.

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