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Porcelain powder coating is a functional powder coating characterized by ultra-high hardness (6H–9H), Class A fire resistance, and excellent weather resistance, giving the coating a ceramic-like texture. It is mainly used for porcelain-coated aluminum panels and in high-frequency impact areas such as rail transit and public buildings.

This article systematically introduces the concept, features, functions, application fields, selection considerations, and solutions to common problems of porcelain powder coating, with a particular focus on the applications of porcelain powder coating, to help you better understand what porcelain powder coating is and what functions it provides.

What Is Porcelain Powder Coating

Porcelain powder coating is a functional powder coating whose core selling points are ultra-high hardness and a ceramic-like texture. Its film-forming materials are organic resins, such as epoxy-modified polyacrylate, polyester, and polyurethane.

Features of Porcelain Powder Coating

Porcelain powder coating has the following features.

1. Ultra-High Hardness and Wear Resistance

This is the core performance characteristic of porcelain powder coating, with a hardness level far exceeding that of ordinary powder coatings.

(1) Hardness Level: The pencil hardness of the coating can reach 6H to 9H. Products at the 6H level generally meet the AAMA 2604 standard and are suitable for outdoor building curtain walls; 9H products achieve their performance through inorganic/ceramic modification, focusing on extreme scratch resistance and are suitable for high-frequency impact areas such as aluminum panels in subway stations.

(2) Wear Resistance: High hardness directly translates into scratch resistance. Scraping from luggage wheels, impacts from cleaning carts, and scratches during installation and handling are less likely to leave marks. Aluminum panels in subway stations can maintain a clean appearance even after five to ten years of use.

2. Fire Resistance and Weather Resistance

(1) Fire Resistance Rating: The coating passes Class A fire-resistance and flame-retardant verification, meeting the fire safety acceptance requirements of public places such as subways, high-speed railway stations, and airports from the material side.

(2) Weather Resistance: Some products pass 4000h xenon-arc aging tests and meet Qualicoat Class 2 powder coating standards, providing resistance to acid rain and atmospheric pollutants and making the coating less likely to yellow or fade under prolonged outdoor exposure.

(3) Heat Aging Resistance: Patents indicate that epoxy-modified polyacrylate resin can significantly improve the heat resistance and aging resistance of the coating while preventing the coating from becoming dark or yellow due to microbial activity, thereby maintaining light diffusion properties over a long period.

3. Self-Cleaning and Easy Maintenance

(1) Dense Low-Surface-Energy Coating: The coating has a high crosslinking density and low surface energy, making dust and oily stains less likely to become embedded.

(2) Easy Cleaning: Daily floating dust can largely be removed by rainwater; localized stains can be wiped clean with a damp cloth; the coating also has anti-graffiti properties, making it difficult for stains to leave marks on the surface.

Functions of Porcelain Powder Coating

The functions of porcelain powder coating are as follows.

1. Resistance to Physical Damage: Ultra-High Hardness and Scratch Resistance

This is the most direct function of porcelain powder coating. The pencil hardness of the coating can reach 6H to 9H, significantly higher than the 1H–2H of ordinary powder coatings. This hardness enables the surface to resist daily physical impacts such as friction from luggage wheels, impacts from cleaning equipment, and scratches during installation and handling. Aluminum panels in subway stations can maintain a clean appearance even after long-term, high-frequency use, significantly reducing refurbishment costs.

2. Ensuring Public Safety: Class A Fire Resistance and Flame Retardancy

Porcelain powder coatings generally pass Class A fire-resistance and flame-retardant verification and do not release toxic smoke during a fire, meeting the mandatory fire safety acceptance requirements of public places such as subways, high-speed railway stations, and airports from the material side. For underground spaces and densely populated areas, this function is directly related to compliance and personnel safety.

3. Reducing Maintenance Costs: Self-Cleaning, Easy Cleaning, and Anti-Graffiti

The coating has a high crosslinking density and low surface energy, making dust and oily stains less likely to become embedded. Daily floating dust can largely be removed by rainwater, while localized stains can be wiped clean with a damp cloth. Some porcelain coatings have a surface tension as low as 22–23 dynes, making it difficult to attach small advertisements and preventing graffiti from marker pens, thereby reducing deliberate damage to public facilities at the source.

4. Extending Service Life: Weather and Corrosion Resistance

The coating provides resistance to acid rain and atmospheric pollutants. Some products pass 4000h xenon-arc aging tests and meet Qualicoat Class 2 and AAMA 2604 standards, helping buildings maintain their appearance over long periods in harsh climatic environments. For outdoor curtain walls and transportation facilities, this function helps ensure long-term appearance stability and substrate protection.

Applications of Porcelain Powder Coating

Which fields require porcelain powder coating? The specific applications are as follows:

1. Rail Transit and Public Transportation

This is the most typical and largest application area for porcelain powder coating. Decorative surfaces in station halls and platforms of subway stations, high-speed railway stations, and airport terminals, especially areas below 1.8 meters that are prone to impacts, commonly use porcelain-coated aluminum panels as wall materials. Porcelain-coated aluminum panels are also widely used for the interior walls of rail vehicles, replacing traditional fluorocarbon-baked aluminum panels to improve the fire safety rating.

2. Building Curtain Walls and Interior/Exterior Decoration

Porcelain-coated aluminum panels are known as the “third-generation curtain wall aluminum panels” and are widely used for interior and exterior decoration in office buildings, shopping malls, hotels, hospitals, stadiums, exhibition halls, and other buildings. Outdoor curtain walls, indoor ceilings, column and beam cladding, and background walls are all common application areas. In areas such as tunnels and column grids where higher strength is required, porcelain-coated steel panels or porcelain-coated stainless steel panels are used.

3. Home Furnishing and Industrial Applications

In industrial and consumer product applications, porcelain powder coating can be used for coating high-temperature steam pipes, heat exchangers, kitchen utensils, and household appliances, taking advantage of its high-temperature steam resistance and corrosion resistance. In home building materials, it is suitable for bathroom and plumbing products, high-end doors and windows, furniture, and other products that require durability and easy cleaning.

How to Select Porcelain Powder Coating

When selecting porcelain powder coating, we may face the problem of not knowing how to choose. Based on our industry experience, we recommend focusing on the following aspects when selecting porcelain powder coating.

1. Determine the Hardness Level According to the Wear Intensity

Hardness is the core selection criterion for porcelain powder coating, but higher hardness is not always better. Instead, it should match the actual wear intensity of the application scenario.

(1) 9H Level (Highest Wear Scenarios): Suitable for subway stations, high-speed railway stations, airports, and other high-traffic areas, especially impact-prone walls below 1.8 meters. 9H porcelain powder coating achieves its performance through inorganic/ceramic modification. Scraping from luggage wheels, impacts from cleaning carts, and scratches during installation and handling are less likely to leave marks, and indoor warranties can reach 10–15 years. If your project has extremely high requirements for durability, choose 9H.

(2) 6H Level (General Public Spaces/Architectural Decoration): Suitable for interior and exterior walls of shopping malls, hospitals, and office buildings. 6H products meet Qualicoat Class 2 and AAMA 2604 standards, have a coating hardness of ≥6H, and pass 4000h xenon-arc aging tests, achieving a balance between weather resistance and cost. If there is no extreme wear, 6H is sufficient and offers higher cost-effectiveness.

2. Verify Fire Resistance and Weather Resistance Certifications

(1) Fire Resistance Certification: For public projects such as subways, high-speed railway stations, and hospitals, confirm that the product has a clear Chinese national standard Class A fire-resistance test report. 9H porcelain powder coating is clearly labeled as “meeting the national Class A fire-resistance standard,” matching the logic of fire safety acceptance from the material side.

(2) Weather Resistance Certification: For outdoor applications, pay attention to AAMA 2604 or Qualicoat Class 2 certification. Super-durable polyester powder coating undergoes 2000h xenon-arc accelerated aging and Florida exposure tests. Its gloss retention and color retention performance are significantly better than those of ordinary comparable products, meeting the requirements of AAMA 2604 and Qualicoat Class 2.

3. Confirm Compatibility Between Curing Conditions and the Production Line

The performance of porcelain powder coating depends heavily on complete curing. During selection, be sure to confirm whether your oven can reach the required workpiece temperature for the product (rather than the oven temperature). The typical curing conditions for powder coatings are 190–200°C, with the time varying according to the product. The “one coating, one baking” process is used during application, and conventional electrostatic spraying equipment can be used, making it suitable for the mass production of aluminum panels, aluminum profiles, and other metal building materials.

Common Problems and Solutions for Porcelain Powder Coating

The most common problems encountered during the use of porcelain powder coating are mainly reflected in the following aspects. Based on our industry experience, we propose corresponding solutions to help effectively solve the powder coating problems you encounter.

1. Coating Cracking and Peeling

Problem: Cracks appear in the coating after curing, or the coating peels or detaches from the substrate. Patent data show that when the curing temperature exceeds 220°C, rapid drying of the surface layer causes uneven internal stress distribution, which can easily lead to cracking. When the curing temperature is below 180°C, the coating cannot fully melt and level, becoming softer and reducing hardness, which can also easily lead to peeling.

Possible Causes: In addition to deviation from the curing window, excessive coating thickness is another major cause. The total thickness of a porcelain coating is generally controlled at 10–40μm (primer + topcoat, 5–20μm each). Excessive topcoat thickness increases the viscosity of the coating and reduces leveling performance, directly leading to cracking. In addition, if the aluminum panel does not undergo sufficient sandblasting pretreatment, the inorganic coating cannot effectively interlock with the smooth aluminum substrate, resulting in inherently insufficient adhesion.

Solution: Strictly control the curing temperature at 180–200°C for 10–30 min. Control the primer and topcoat thickness at 10–15μm each. The aluminum panel must undergo sandblasting treatment to form a rough surface with an uneven texture, serving as an intermediate layer between the inorganic coating and aluminum substrate and enabling the coating to adhere firmly.

2. Brittle Coating and Poor Impact Resistance

Problem: Although the coating has a pencil hardness of 9H, it is prone to cracking and peeling when subjected to impact or when the substrate is subsequently bent, showing characteristics of being “hard but brittle.”

Possible Causes: 9H hardness is achieved through inorganic/ceramic modification. While the high crosslinking density provides scratch resistance, it also significantly limits the deformability of the coating. Once the crosslinked structure of the powder coating has cured, it cannot adjust flexibility through plasticizers in the same way as liquid coatings. Excessive coating thickness further increases internal stress and reduces effective elongation.

Solution: Prioritize products that balance hardness and flexibility. Avoid the issue through process design—complete bending operations before spraying whenever possible to prevent the coating from undergoing secondary mechanical deformation.

3. Particles and Protrusions on the Coating Surface

Problem: Protruding particles appear on the coating surface after curing, affecting the smooth and glossy appearance expected of porcelain coatings.

Possible Causes: Porcelain powder is extremely sensitive to moisture. During electrostatic dry powder porcelain spraying, excessive environmental humidity or moisture in compressed air can cause the powder to absorb moisture, adhere, and form agglomerates. When these powder agglomerates are sprayed and deposited onto the surface of components, they form protruding defects during firing. This differs from the cratering mechanism of ordinary powder coatings and is a moisture-induced agglomeration problem specific to porcelain powder.

Solution: Isolate the spraying area and install a dehumidifier. Sieve the powder before use. Compressed air must undergo oil and water removal treatment. Control the humidity of the spraying environment to prevent powder from agglomerating in the fluidizing box and conveying lines.

Get a Customized Porcelain Powder Coating Solution

Are you looking for a powder coating that combines a porcelain-like texture, decorative effects, and surface protection performance?

We are a China powder coating manufacturer with 20+ years of industry experience. Based on different substrates, application fields, colors, gloss levels, surface effects, and performance requirements, we can provide customers with customized porcelain powder coating solutions.

Whether you need standard porcelain-effect powder coating or a customized product developed for a specific application, we can provide product matching and technical communication according to your specific requirements.

Contact us to obtain:

• Product specifications and technical parameters
• Color and surface effect solutions
• Customized powder coating solutions
• Product samples
• Technical selection recommendations
• Product quotations

Please tell us your substrate type, application field, color requirements, performance requirements, and spraying process. Our team will recommend a suitable powder coating solution based on your requirements.