Why is surface treatment so important?
The reason why stainless steel is "rust-proof" mainly depends on a very thin and strong chromium-rich oxide film (passivation film) on its surface. The surface treatment process not only determines the appearance and texture of the product, but also directly affects the shape and integrity of this protective film, and thus is related to its corrosion resistance, wear resistance, cleaning difficulty and subsequent processing performance. Choosing the right surface is the first step to ensuring that the material is fully utilized.
Details of surface treatment processes
Different surfaces have different processing details and procedures.
2B Finish (Cold-rolled surface, standard matte finish)
Process: After cold rolling, it undergoes heat treatment, pickling, and finally flat rolling.
Appearance features: It has a matte silver-white appearance, a uniform surface, low gloss, and fine longitudinal lines.
Core features: The most universal and fundamental commercial-grade surface. It has good surface consistency and moderate corrosion resistance, and is easy to undergo subsequent mechanical processing or simple polishing treatment.
BA Finish (Bright annealed surface)
Process: Bright heat treatment is carried out in a controlled atmosphere (such as a hydrogen-nitrogen mixture) annealing furnace to prevent surface oxidation, followed by a slight leveling.
Appearance features: Highly reflective, mirror-like bright, extremely clean surface, free of oxide scale.
Core features: It can achieve a bright surface without acid washing and has excellent corrosion resistance (as there is no risk of trace element residue or hydrogen embrittlement caused by acid washing). However, its surface is relatively "soft" and prone to scratches, so it needs extra protection during transportation and processing.
NO.4 Finish
Process: Mechanically polish the 2B or BA surface, using grinding materials of moderate particle size to produce continuous short lines.
Appearance features: It has a directional matte filamentous texture, with fine and uniform lines and a modern feel. It can be classified into straight texture (HL), random texture (snowflake sand), etc.
Core features: Beautiful and practical. The texture can effectively cover up small scratches produced during daily use, and it has a good hand feel and moderate cleanliness. Its corrosion resistance is superior to that of the original 2B surface.
HL Finish
Process: It can be regarded as a type of No.4. Usually, coarser abrasive materials are used to grind out continuous and straight long lines, which are clearer and deeper than those of No.4.
Appearance features: It has clear, continuous and textured straight hairline patterns, with a stronger sense of industrial design and lines.
Core features: Outstanding decorative effect, effectively concealing defects. However, the grooves in the patterns may be more prone to dirt accumulation than other planes.
How to choose the right surface treatment?
Usage environment and corrosion resistance requirements
Harsh environments (coastal, chemical, food and pharmaceutical) : BA surface (the best passivation film) is preferred, followed by No.4 or HL that has undergone good passivation treatment.
For general indoor/dry environments: A 2B surface is usually sufficient and cost-effective.
Frequent contact and scratch-prone environments: The No.4 surface is a more durable choice due to its texture that can cover up small scratches.
Aesthetics and design requirements
Modern simplicity and a sense of technology: The straight texture of HL or No.4 is the top choice.
High cleanliness and brightness (such as in laboratories and kitchens) : BA surface.
Industrial style, emphasizing functionality: The original texture of the 2B surface is sufficient.
Subsequent processing and maintenance costs
Welding, bending and other processing are required: The 2B surface has the most advantages and the highest tolerance.
It is hoped to reduce the frequency of daily cleaning and maintenance: Avoid choosing BA surfaces that are prone to water stains and fingerprints. Matte surfaces such as No.4 are more friendly.
Difficult to reach and maintain after installation: A surface with a higher corrosion resistance grade should be selected, even if the initial cost is slightly higher
Comprehensive budget
The price ranking is usually: BA > HL ≈ No.4 > 2B. It is necessary to balance the initial material cost with the maintenance and replacement costs throughout the entire life cycle.
Conclusion
There is no such thing as the "best" surface; there is only the "most suitable" choice. Understanding the essential differences among processes such as 2B, BA, HL, and No.4 is the foundation for making wise decisions.
Post time: Jan-22-2026
