Color-coated sheet: functional coated sheet with both good looks and performance

In fields such as architectural decoration, home appliance manufacturing, and transportation equipment, color-coated steel, with its core advantages of "substrate strength combined with the decorative and weather-resistant properties of a colored coating," has become a highly effective alternative to the "normal steel plate + post-painting" method. Made from cold-rolled steel, galvanized steel, or stainless steel, it undergoes surface pretreatment (degreasing and phosphating), roller-coated with a colored organic coating (primer and topcoat), and then high-temperature curing. While inheriting the mechanical properties of the substrate, the coating eliminates the need for secondary painting, offers corrosion resistance, and allows for customizable colors. Widely used in applications such as factory buildings, appliance housings, shipping containers, and integrated housing, it is a key material that balances aesthetics and practicality in both industrial and consumer sectors.

I. Basic Concepts and Core Components of Color-Coated Steel

Color-coated steel is essentially a composite structure of "substrate + functional coating." Its core value lies in addressing the shortcomings of ordinary steel: rust, the need for post-painting, and monotonous color. Its core components include two parts:

(I) Baseplate: Determines basic strength and corrosion resistance

The baseplate is the "skeleton" of the color-coated steel sheet, directly affecting the sheet's load-bearing, bending, and welding properties. Main types are divided into three categories:

Cold-rolled baseplate: Based on cold-rolled steel sheet (thickness 0.15-2.0mm), it features a smooth surface and high dimensional accuracy, but weak corrosion resistance (no anti-rust coating) and is only suitable for indoor applications (such as appliance back panels and furniture panels) and requires a thick coating for improved weather resistance.

Galvanized baseplate: Based on hot-dip galvanized steel sheet (GI) or electrogalvanized steel sheet (EG), the surface contains a zinc layer of 50-275g/㎡ (hot-dip galvanizing) or 10-20g/㎡ (electrogalvanizing). It offers superior corrosion resistance to cold-rolled baseplate and is the primary choice for outdoor applications (such as building wall panels and billboards).

Stainless steel baseplate: Based on 304/430 Stainless steel plate is the base material and has the strongest corrosion resistance, but it is expensive and is only used in high-end scenarios (such as medical furniture and marine environment decorative panels). The coating mainly serves as decoration and anti-fingerprint function. (II) Coating: Imparting Decorative and Functional Properties

The coating is the outer layer of the color-coated sheet. It is applied using a roller coating process (high efficiency and uniform coating) or a spray coating process (suitable for complex textures). The typical coating structure is "primer + topcoat." Some high-end products also have a "backcoat" (to prevent backside corrosion) or a "clearcoat" (to enhance gloss and scratch resistance):

Primer: 5-10μm thick, primarily serves to enhance adhesion between the substrate and the topcoat while also improving corrosion resistance (epoxy resin and polyester resin are commonly used);

Topcoat: 15-25μm thick, determines color, texture, and weather resistance. Main resin types:

Polyester (PE): Cost-effective, moderate weather resistance (5-8 years of outdoor wear resistance), suitable for factory wall panels and appliance housings;

PVDF: Excellent weather resistance (15-20 years of outdoor wear resistance), UV resistance, acid and alkali resistance, suitable for high-rise building curtain walls and marine environments;

Silicon-modified polyester (SMP): Weather resistance between PE and PVDF (8-12 years outdoor life), with high hardness and scratch resistance, is suitable for roofing panels and traffic signs.
Texture: In addition to solid colors, embossing can be used to create textures such as wood grain, stone grain, and leather grain, simulating natural materials (for example, wood-grain color-coated panels are used for interior walls in integrated housing).

Common specifications for color-coated panels: Thickness 0.15-2.0mm (mainstream 0.3-0.8mm), width 1000-1250mm, lengths customizable (typically 1-6m), or supplied in rolls (color-coated rolls, suitable for continuous processing).

II. Core Classification of Color-Coated Panels (Based on Substrate and Performance)

The classification logic for color-coated panels revolves around "substrate type" and "coating performance," which together determine their application scenarios. The main classifications are as follows:

(I) Classification by Substrate Type (Basic Dimension)

Cold-Rolled Color-Coated Panels

Features: Smooth surface and lower cost than galvanized substrates, but with weaker corrosion resistance (no zinc layer) and should be protected from outdoor rain.
Applications: Indoor appliance housings (such as refrigerator side panels and washing machine back panels), furniture panels (cabinet door panels), and interior decorative partitions. Typical coatings are PE resins (low cost and suitable for indoor weather resistance).

Galvanized base color-coated steel sheets (approximately 70%)

Subcategories include:

Hot-dip galvanized (GI) color-coated steel sheets: Thick zinc layer (50-275g/㎡), strong corrosion resistance, suitable for outdoor applications (such as factory roofs and integrated housing wall panels);

Electrogalvanized (EG) color-coated steel sheets: Thin zinc layer (10-20g/㎡), smoother surface, suitable for high-end appliance housings (such as air conditioner outer casings and microwave oven panels).

Applications: Outdoor buildings (60%), appliance housings (30%), and transportation facilities (10%). Coatings are typically PE or SMP resins. Stainless Steel Color-Coated Sheet

Features: Extremely corrosion-resistant (the substrate itself is rust-resistant). The coating serves only as a decorative and fingerprint-resistant finish. Cost is high (3-5 times that of galvanized color-coated sheet).

Applications: Medical furniture (such as sterile ward cabinets), offshore platform decorative panels (salt spray resistant), and high-end commercial space walls (such as shopping mall counters). The coating is typically PVDF or antibacterial resin.

Other Specialty Color-Coated Sheet

Aluminum Color-Coated Sheet: Lightweight (density 2.7g/cm³, only 1/3 that of steel) with excellent thermal conductivity, suitable for lightweight applications (such as RV hulls and aircraft interiors).

Aluzinc Color-Coated Sheet: Contains an aluminum-zinc alloy layer (55% aluminum, 43.4% zinc, and 1.6% silicon) on the surface. Its weather resistance surpasses that of hot-dip galvanized sheet (12-15 years outdoor life). It is used for roofing panels with high weather resistance requirements (such as large venues). (II) Classification by Coating Performance (Functional Dimension)
Weather-Resistant Color-Coated Sheets
Coating: PVDF or SMP resin with added UV absorbers. Weatherability ≥ 8 years (SMP) or ≥ 15 years (PVDF). Color difference ΔE ≤ 3 (5 years outdoor).
Applications: High-rise building curtain walls, outdoor billboards, and factories in coastal areas. For example, PVDF color-coated sheets are used on the exterior walls of the Shenzhen Ping An Finance Center (weatherability over 20 years). Functional Color-Coated Sheets
Antibacterial Color-Coated Sheets: Silver/Zinc ions are added to the coating, achieving an antibacterial rate of ≥99% (against E. coli and Staphylococcus aureus). Suitable for hospital walls and food factory workshops.
Self-Cleaning Color-Coated Sheets: Nano-TiO₂ coating removes stains with rainwater (contact angle ≥110°). Suitable for high-rise building exteriors and photovoltaic panel backsheets.
Thermal Insulation Color-Coated Sheets: Hollow microspheres are added to the coating, achieving a solar reflectivity of ≥80%, reducing indoor temperatures by 3-5°C in summer. Suitable for factory roofs and prefabricated houses.
Decorative Color-Coated Sheets
Coating: PE or matte PVDF resin, with textures such as wood grain, stone grain, and brushed metal, simulating natural materials without the need for post-decoration.
Applications: Interior walls of prefabricated houses (wood grain), department store counters (brushed metal), and furniture door panels (stone grain). For example, wood-grain color-coated sheets are used on interior walls of prefabricated houses, eliminating the need for wallpaper after installation.

III. Key Performance Advantages of Color-Coated Steel Sheets (Compared with Ordinary Steel and Stainless Steel Sheets)

The performance advantages of color-coated steel sheets lie in the combined strength of the base material and the functionality of the coating, precisely addressing the pain points of using traditional sheet materials:

Decorative Features: From "Single Gray" to "Thousands of Colors and Patterns"

Ordinary steel sheets are available only in silver-gray or black, requiring later painting (which is prone to fading and expensive). Color-coated steel sheets can be customized in over 200 colors (such as the full RAL color palette) and over 10 textures (such as wood and stone). The final decorative effect is achieved immediately after installation, eliminating the need for painting (reducing costs by 30%-50%). For example, wood-grain color-coated steel sheets for prefabricated homes achieve the same visual effect as solid wood walls, but at only one-third the cost of solid wood. Weather Resistance: From "Rust in 1-2 Years" to "15-Year Maintenance-Free"

Ordinary cold-rolled steel sheets rust outdoors after 1-2 years and require annual painting and maintenance. Galvanized steel sheets with color-coated (PE-coated) panels remain fade- and rust-free for 5-8 years outdoors. PVDF coatings can extend this to 15-20 years, with virtually zero maintenance costs. For example, the average annual maintenance cost for a factory roof is 20 yuan/㎡ for an ordinary steel roof, while the total cost for a PVDF color-coated roof over 15 years is only 50 yuan/㎡ (initial + zero maintenance).

Processability: From "Difficult to Bend" to "Flexible Formability"

Color-coated steel sheets retain the bending properties of the base material, enabling 90° cold bending (radius ≤ 2 times thickness), stamping (such as for concave and convex shapes on appliance housings), and shearing (cutting to length). The coating is also highly resistant to flaking (adhesion ≥ 5MPa, no paint peeling in a cross-cut test). For example, EG-based color-coated sheet for air conditioner exterior casings can be stamped in a single step, requiring no subsequent processing.

Economics: From "High Overall Cost" to "Optimal Cost-Effectiveness"

Comparing three types of sheet materials (taking 0.5mm thick outdoor wall panels as an example):

Ordinary steel sheet + paint: Initial cost 30 yuan/㎡, 5-year maintenance cost 50 yuan/㎡, total 80 yuan/㎡;

Galvanized color-coated sheet (PE coating): Initial cost 45 yuan/㎡, 5-year maintenance cost 0 yuan, total 45 yuan/㎡;

Stainless steel sheet: Initial cost 150 yuan/㎡, 5-year maintenance cost 0 yuan, total 150 yuan/㎡;

The overall cost of color-coated sheet is only 56% of that of ordinary steel sheet and 30% of that of stainless steel sheet, offering significant cost-effectiveness.

IV. Key Application Areas of Color-Coated Steel Sheets

The "decorative + weather-resistant + low-cost" properties of color-coated steel sheets make them suitable for a wide range of applications, including construction, home appliances, transportation, and furniture. The core applications are as follows:

(I) Construction (approximately 60%)

Industrial plants: Hot-dip galvanized PE color-coated steel sheets (0.3-0.5mm) for roof and wall panels, offering 5-8 years of weather resistance and easy installation (using snap-fit ​​connections, eliminating the need for nailing). For example, automobile factories use blue PE color-coated steel sheets, balancing both visual recognition and weather resistance.

Prefabricated housing: Hot-dip galvanized PVDF color-coated steel sheets (0.4-0.6mm) for interior and exterior wall panels. These panels are prefabricated in the factory and assembled on-site (reducing construction time by 50%). For example, prefabricated housing in temporary post-disaster resettlement sites, using only color-coated steel sheets, can be constructed in just 10 days.

High-rise buildings: Aluminum-zinc-coated PVDF color-coated steel sheets (0.6-0.8mm) for curtain walls, offering weather resistance. 15-20 years of UV resistance (preventing fading). For example, the silver-gray PVDF color-coated panels used on the exterior walls of Shanghai's Hongqiao Tiandi shopping mall have shown no noticeable color change after 10 years.

Municipal facilities: Self-cleaning color-coated panels (0.5mm) are used for bus stop roofs and outdoor billboards. Rainwater washes away dust, reducing manual cleaning costs (saving 80 yuan/m2 annually). (II) Home Appliances (approximately 20%)

White appliances: Electrogalvanized PE color-coated steel sheets (0.3-0.5mm thick) are used for refrigerator side panels, washing machine backs, and air conditioner exterior casings. They offer a smooth surface (suitable for logo printing) and are scratch-resistant (hardness ≥ 2H).

Black appliances: Matte PE color-coated steel sheets (0.4mm thick) are used for TV backs and microwave oven casings. They are fingerprint-resistant (surface resistance 10⁸-10¹⁰Ω and anti-static).

Small appliances: Thin-gauge cold-rolled color-coated steel sheets (0.15-0.2mm thick) are used for rice cooker casings and electric kettle bases. They are lightweight (10% lighter than ordinary steel sheets) and easy to form. (III) Transportation and Logistics (approximately 10%)
Containers: Hot-dip galvanized, wear-resistant PE color-coated steel sheets (0.8-1.2mm) are used for container side and roof panels. They are impact-resistant (impact strength ≥ 20kJ/m²) and seawater corrosion-resistant (rust-free after 5 years of sea transport).
RVs and Special Vehicles: Aluminum-coated, color-coated steel sheets (0.5mm) are used for RV hulls. They are lightweight (60% lighter than steel-coated steel sheets) and offer excellent thermal conductivity (insulating in summer and retaining heat in winter).
Traffic Signs: Highly reflective color-coated steel sheets (0.4mm) are used for road signs. They have a reflectivity of ≥ 70% (visible at night from a distance of ≥ 300 meters) and are weather-resistant for 8 years or more. (IV) Furniture and Decoration (approximately 10%)

Furniture panels: Cold-rolled wood-grain color-coated sheets (0.3-0.4mm) are used for cabinet doors and wardrobe side panels. They eliminate the need for veneer (reducing costs by 40%) and are mildew-resistant (no deformation in humid environments).

Indoor partitions: Matte PVDF color-coated sheets (0.5mm) are used for office glass partition frames. They are aesthetically pleasing (with a metallic finish) and stain-resistant (easy to wipe).

Exhibit fixtures: Brushed metal color-coated sheets (0.4mm) are used for shopping mall counters and exhibition booths. They require no polishing after installation (with an even surface gloss) and are reusable.
V. Future Development Trends of Color-Coated Steel Sheets

With the increasing demand for green buildings and high-end manufacturing, color-coated steel sheets are developing towards environmental friendliness, functionality, thinness, and customization:

Environmental friendliness: Solvent-free coatings and recycling

Replacing traditional solvent-based coatings (containing VOCs) with solvent-free powder coatings (VOC emissions ≤ 10g/L) and water-based coatings (soluble in water, odorless) are being promoted, complying with EU CE and China GB 18581 environmental standards. A color-coated steel sheet recycling system is being established, where waste color-coated steel sheets can be separated from the base and coating (the coating is incinerated at high temperature and the base is recovered), achieving a recycling rate of over 90%, reducing solid waste pollution. Functionalization: Multiple performance enhancements overcome application limitations.

Development of "multifunctional composite color-coated sheets": such as "antibacterial + thermal insulation + self-cleaning" three-in-one color-coated sheets (used on hospital roofs, simultaneously meeting sterility, cooling, and low maintenance requirements); "photovoltaic-compatible color-coated sheets" (coated with a transparent conductive coating, suitable for use as photovoltaic panel backsheets, achieving both power generation and decorative benefits); and "fire-resistant color-coated sheets" (with an oxygen index ≥ 32%, achieving Class B1 fire protection, suitable for high-rise building exteriors).

Thinness: Highly weather-resistant thin substrates reduce costs and weight.

Development of "thin-substrate, highly weather-resistant color-coated sheets": such as a 0.2mm thick hot-dip galvanized substrate with a PVDF coating. By increasing the zinc layer thickness (200g/㎡) and improving coating adhesion, the sheets achieve the same weather resistance as 0.3mm thick traditional color-coated sheets, while reducing weight by 30% and costs by 20%. These sheets are suitable for lightweight applications such as drone landing pads and temporary exhibition halls. Customization: Personalization and Deep Adaptation to Scenarios

We offer a full-chain customization service: from color (matching the client's brand color), texture (replicating natural stone/wood), to performance (adjusting weather resistance, antibacterial, and thermal insulation parameters as needed). We can even customize custom shapes and sizes (such as curved color-coated panels for stadium domes). Integrating digital technology, we use 3D simulations to visualize the installation effect, meeting individual client needs (such as artistic exterior walls for high-end commercial spaces).

Conclusion

As a "functional upgrade of traditional steel panels," color-coated panels, with their core advantages of "ready-to-install, aesthetically pleasing, and cost-effective," have reshaped the material selection process for architectural decoration and home appliance manufacturing. They address the cumbersome issues of ordinary steel panels (prone to rust and requiring painting) while also addressing the limitations of stainless steel panels (high cost and monotonous color), becoming a "bridge material" connecting industrial production and everyday life. From the blue roofs of factories to...From the colorful exteriors of home appliances to the wood-grained interior walls of prefabricated homes and the silver curtain walls of high-rise buildings, color-coated steel sheets are present throughout the entire "production-life-ecology" landscape. In the future, with breakthroughs in environmentally friendly coatings and multifunctional technologies, color-coated steel sheets will further develop in a greener, smarter, and more personalized direction, becoming a "functional foundational material" supporting green buildings and high-end manufacturing.