The surface treatment process of the stainless steel handle for the room is the core technical guarantee for its corrosion resistance, aesthetics and functionality, especially in a humid environment where it needs to resist moisture, chemicals and frequent contact. The following reveals the key processes and technical points:

 

1. Passivation

Stainless steel naturally forms a protective chromium oxide film in the air, but iron filings (from cutting tools) or contaminants embedded during processing can damage this film. Passivation is carried out by soaking in nitric acid (20-40% concentration, 50-60°C) or organic acids to remove free iron, increase the density of the chromium oxide layer, and significantly enhance the anti-rust ability. Key step: First, thoroughly degrease (do not use chlorine-containing solvents), otherwise the residual oil will cause bubbles in the acid bath or "flash etching" (surface blackening and etching).

 

2. Mechanical Polishing

Create a **#3 satin finish ** through progressive grinding belts (such as 100-120 mesh abrasive belts), or achieve a **#8 mirror finish ** (reflectivity > 90%) with polishing paste oil polishing. Polishing not only enhances the luster but also reduces surface micro-gaps, lowering the risk of scale adhesion and corrosion.

 

 Decorative and functional coatings

3. Wire Drawing

Use a nylon wheel or abrasive belt to scrape the surface in a directional manner to create a uniform matte texture (such as straight lines or cross lines). This process hides scratches and provides an anti-slip grip, making it suitable for bathrooms that are frequently used.

 

4. PVD coating (Physical Vapor Deposition)

In a vacuum chamber, metal ions such as titanium and zirconium are deposited onto the surface of the handle, generating colors like black, gun gray, and rose gold. PVD coating is more wear-resistant and corrosion-resistant than electroplating, and it does not emit harmful chemical solutions. High-end brands apply this process to hotel-grade bathroom hardware, combined with anti-fingerprint technologies (such as nano-silica coating), to reduce the frequency of cleaning.

 

5. Electrolysis Coloring (Electrochemical coloring

Stable interference colors (such as bronze, deep blue) are generated through anodic oxidation in an acidic bath. Temperature control is crucial - exceeding 330°C will cause the color to fade to black.

 

Anti-fingerprint (AF) coating: Nano-silica or fluoride fills the surface micropores, reducing surface energy and making it difficult for oil stains to adhere. Cleaning only requires neutral detergent.

Antibacterial coating: Silver ions are integrated into the PVD layer to inhibit the growth of microorganisms such as Escherichia coli, making it suitable for hospitals and household bathrooms.