Powder coating plays a crucial role in protecting and enhancing the appearance of sheet metal products. For sheet metal suppliers, achieving a high-quality finish is essential to ensure durability, aesthetic appeal, and customer satisfaction. However, common powder coating issues can lead to costly rework, production delays, and reduced product quality. This guide outlines the most frequent problems encountered in powder coating, their causes, and the best practices to ensure flawless results.
The coated surface appears uneven or textured, resembling the skin of an orange. This issue often arises from incorrect spray gun settings, improper curing temperatures, or poor surface preparation. When the coating is applied too thickly or at an incorrect distance, the powder may not flow properly, resulting in an inconsistent finish. Ensuring proper calibration of equipment, maintaining the correct curing temperature, and using quality powder coating materials can significantly reduce this problem.
MCL’s standard underscores the importance of uniform application: maintaining proper spray distance, powder thickness, and accurate curing temperatures. When inspecting for orange peel, the surface is typically viewed from 2.0 metres in normal lighting (320–500 lux), as specified by the AS3715–2002 standards.
Small holes or bubbles may appear on the coated surface, compromising the integrity of the finish. These defects are usually caused by contaminants such as oil, grease, or moisture trapped in the substrate before coating. Impurities within the metal itself can also lead to gas emissions during the curing process, forming tiny air pockets within the coating. To prevent pinholes, it is crucial to thoroughly clean and degrease the surface before applying the powder. Additionally, ensuring proper ventilation in the curing oven helps prevent the formation of bubbles.
Coatings that peel or chip easily often result from inadequate cleaning, insufficient pretreatment, or incorrect curing. If the substrate is not properly prepared, the powder may not bond effectively, leading to adhesion failures. Mechanical or chemical pretreatment, such as sandblasting or phosphate coating, can improve adhesion. Ensuring that the curing process reaches the recommended temperature and duration is also essential for achieving a durable bond.
MCL’s process includes chemical pretreatment - such as phosphate coating - to promote bonding. Curing times and temperatures follow manufacturer recommendations and are verified by test panels and thickness gauges.
Inconsistent colour across the coated surface can be caused by uneven application, contamination of the powder, or variations in curing temperatures. Factors such as inconsistent powder thickness, improper mixing of different batches, or environmental conditions like humidity can impact the final appearance. To achieve a uniform colour, it is important to use high-quality, well-stored powder and maintain a consistent application technique.
We recommend storing powder in a controlled environment, using fresh batches promptly, and maintaining consistent spraying techniques. Any colour irregularities are checked under standard viewing conditions at 2.0 metres.
Some areas of the metal may remain exposed or appear inadequately coated due to incorrect spray techniques, poor equipment calibration, or blockages in the spray gun. If the powder is not applied evenly, it may result in insufficient coverage, leading to weak spots in the coating. Regular maintenance of spraying equipment and proper training for operators can help ensure even coverage and reduce waste.
Proper preparation is key to achieving a flawless powder coat finish. Metal surfaces should be thoroughly cleaned, degreased, and/or abraded to remove contaminants before coating. Techniques like sandblasting or chemical pretreatment enhance adhesion and improve durability. Removing rust, mill scale, and previous coatings is essential to ensure a smooth application.
Regular calibration of spray guns and curing ovens ensures accuracy and consistency. Frequent monitoring of air pressure, voltage, and spray distance prevents uneven coatings and common defects. Ensuring that nozzles and filters are clean and free from obstructions will help maintain a smooth and even application.
Storage conditions significantly impact powder quality. Keeping powder in a controlled environment prevents contamination and moisture absorption. Humidity can cause powder to clump, leading to inconsistent application. Using fresh powder and avoiding the mixing of old batches maintains consistency in application and colour. Proper handling, including wearing protective gloves, also prevents contamination from oils or dirt.
Following manufacturer-recommended curing temperatures and times is essential for proper fusion. A temperature gauge should be used to monitor even heat distribution in the curing oven, preventing defects like orange peel and poor adhesion. An uneven curing process can result in a fragile coating that does not adhere properly, so ensuring an even heat supply throughout the oven is crucial.
Proper application techniques contribute to a uniform finish. Training staff on correct spray methods and maintaining a consistent speed, distance, and angle during application ensures even coverage. Operators should avoid excessive build-up in certain areas, as this can lead to defects. Overlapping passes should be controlled to prevent excessive thickness in some areas while ensuring full coverage in others. Well-trained operators achieve the best results while minimising material waste.
Implementing rigorous quality control processes before and after coating helps identify and rectify issues early. Routine equipment maintenance ensures smooth operation and prevents unexpected failures. Conducting visual inspections and thickness measurements ensures that coatings meet the required specifications.
Regular training sessions keep staff updated on the latest industry standards and best practices. Ensuring that operators understand the importance of surface preparation, application techniques, and curing parameters is key to maintaining high-quality results.
Partnering with an experienced powder coating service provider like MCL can make a significant difference. With expertise, advanced facilities, and stringent quality control, MCL ensures that every project meets the highest standards and achieves a flawless finish. By working with a trusted provider, sheet metal suppliers can significantly reduce defects and increase efficiency.
MCL offers state-of-the-art powder coating facilities with advanced equipment and strict quality control processes. With years of experience dealing with sheet metal suppliers and powder coating, we understand the common challenges and have developed refined solutions to prevent defects. From precision surface preparation to expert application techniques, we ensure that every product meets the highest industry standards.
Our team of specialists provides comprehensive support, offering custom finishing options and expert guidance to optimise results. Whether it’s maintaining consistent colour, preventing adhesion issues, or ensuring a durable finish, MCL is the trusted partner for superior powder coating solutions. We continually invest in technology and training to stay ahead of industry advancements, providing our clients with the best possible outcomes.
Achieving a high-quality powder-coated finish requires attention to detail, proper technique, and expert knowledge. By understanding common issues and implementing best practices, sheet metal suppliers can enhance durability, improve product appearance, and reduce costly rework.
With the right surface preparation, application methods, and curing processes, defects can be minimised, leading to a superior final product. Ongoing maintenance of equipment and regular training for operators ensure long-term consistency and quality.
At MCL, we adhere to the strict internal guidelines which reference important industry documents such as AS3715–2002. These guidelines outline how and when surfaces should be inspected, how defects are defined, and what care and maintenance procedures should be followed to ensure a consistent, reliable powder coat.
For professional powder coating services and expert support, contact MCL today. Let us help you achieve a flawless, long-lasting finish that sets your products apart.