In recent years, the popularity of decorative stainless steel has increased due to its primary strength, hardness, corrosion resistance, and the wide range of colors and finishes. Decorative stainless steel demand is projected to increase due to urbanization and demand in the architecture sector in the coming years. Decorative stainless steel can be used for both interior and exterior design, such as in signage, elevator interiors, and feature walls.
The colors in stainless steel shape our emotions, behavior, and separate identity into components. The colored stainless steel increases the life of the material and reduces the need for repairing and repainting.
Main Coloring Methods for Stainless Steel
Physical vapor deposition and Chemical or Electrochemical coating methods are commonly used for coloring on stainless steel. These methods give an excellent appearance, finishing, and long-term performance. The detailed discussion about these methods is given below:
PVD (Physical Vapor Deposition) Coating
In physical vapor deposition, a thin film such as titanium nitride is deposited onto the substrate. The coating material is evaporated in a vacuum chamber and produces a good adhesive film with the substrate. The vacuum ensures the purity and avoids air during deposition.
The physical vapor deposition gives uniformity to the substrate, whether it is large or small products. It gives a more durable film and is more adhesive to the substrate. This method gives a more UV-resistant coating and environmentally friendly deposition onto the substrate. It gives a more finished surface as compared to other methods,
Chemical or Electrochemical Coloring
The chemical or electrochemical coloring can be achieved by inserting the material in the acidic bath, and then an electric current is applied to produce the oxide layer on stainless steel. The thickness of this film will determine the color of the coating, and it can be measured in micrometers. The color arises when light interacts with the oxide film; some of the light will reflect, absorbed by the coating.
The suitable grades are 304, 316, and 430, which allow a stable and uniform layer on the material. The typical color options are blue, gold, green, black, and bronze. The color inconsistency and lower durability make it less durable compared to physical vapor deposition.
Surface Finishes and Texture Effects
The surface finishing and texture are equally important in determining the overall visual impact. The color tone of different coatings is heavily dependent on how the light reflects off them. The more textured and less surface finishing film results in scattering of light, and the color looks more subtle. Similarly, the more finishes and reflective surfaces give brighter colors. Table 1 shows the different finished surfaces, their effect, and applications on stainless steel.
Table-01: Common surface finishes for colored stainless steel
|
Finish |
Description |
Effect |
Applications |
|
Brushed |
polishing the surface with fine abrasive belts |
Matte look, soft color tone. |
Interiors, wall panels. |
|
Bead-Blasted |
Surface treated with fine glass beads. |
Smooth satin texture, soft hue. |
Elevators, cladding. |
|
Embossed |
Mechanically patterned surface. |
3D texture, light scattering. |
Ceilings, doors, public areas. |
|
Etched |
Chemically or laser patterned. |
Textured, contrasting tones. |
Façades, custom designs. |
|
Mirror |
Highly polished reflective surface. |
Bright, vivid color. |
Luxury interiors, décor. |
Durability and Quality Testing
The different testing methods are used to ensure the durability, adhesion of stainless steel coating. Table 02 shows the performance comparison between the PVD and chemical coloring methods. The following testing methods are used for quality assurance:
- Adhesion: The adhesion of the coating with the substrate can be checked by cross cross-hatch test, or under mechanical stress.
- Abrasion: The hardness of stainless-steel coloring can be checked by controlled scratching or rubbing. The physical vapor deposition coating shows more resistance to scratches as compared to oxide-based coatings.
- Ultraviolet resistant: This test determines the stability of the colors, which is shown by coating under UV exposure. The physical vapor deposition shows more resistance to fading of colors as compared to chemical coloring.
- Temperature resistant: The coating substrate is exposed to high temperatures to check the performance. The PVD coating shows more temperature resistance.
- Salt spray, adhesion, abrasion, UV, and temperature resistance tests.
Table 02: Comparison between PVD and chemical coloring performance
|
Property |
PVD Coating |
Chemical/Electrochemical Coloring |
|
Corrosion Resistance |
Excellent; highly stable in saline and humid conditions. |
Good, but may vary depending on oxide layer uniformity. |
|
Adhesion Strength |
Strong metal bonding through vacuum deposition. |
Moderate, oxide layer can wear off under mechanical stress. |
|
Abrasion Resistance |
High, very hard, and scratch-resistant surface. |
Moderate; more prone to wear and dulling. |
|
UV Resistance |
Excellent; color remains stable over time. |
Fair; may show slight fading under prolonged sunlight. |
|
Temperature Stability |
Excellent across wide temperature ranges. |
Limited, high heat may alter oxide color. |
Common Applications
The colored stainless steel is the preferred choice for designers due to its corrosion resistance, durability, and appearance. Due to this reason, it can be used in both the interior and exterior of different applications. The following are some applications of colored stainless steel:
- Elevator panels: They can be used in elevators due to their resistance to scratches, corrosion resistance, and appearance.
- Decorative walls: It can be used for both interior and exterior spaces of projects due to its durability, corrosion resistance.
- Signage: The long-lasting colors and high reflectivity of stainless steel’s coloring materials make it preferred for use the signage.
- luxury interiors: It is preferred to use in houses, offices, buildings, and hotels for luxury interiors. Its shining appearance makes it preferred to use in a luxury interior
Conclusion & Recommendations
The durability, corrosion resistance, and appearance of stainless steel make it a preferred choice in designing and architectural applications. The PVD coating offers the long-lasting life of projects due to its good adhesion of coating with substrate, durability, and uniformity. PVD coating offers a good texture and finished surface for excellent reflectance of light. The technology for coloring the stainless steel is getting advanced day by day to achieve excellent performance. Contact us now to get the latest quotation for colored stainless steel sheet!
