Enhancing the Patina's Protective Performance
◆ This is usually achieved through factory pre-patination optimization:
Adjust the concentration of the S355J2W-specific rust accelerator, and extend the controlled weathering time (to 14–21 days) in a 65% humidity, 22°C environment, to form a thicker (20–30 μm) and denser copper-chromium-rich patina, which can improve resistance to chloride ions in coastal areas by 30–40%
◆ Add a small amount of corrosion-inhibiting additives to the rust accelerator, to further reduce the porosity of the patina and enhance its self-healing speed for minor damage
Modifying the Patina's Aesthetic Color
The natural patina of S355J2W is a uniform reddish-brown, and its color can be modified through controlled treatment:
◆ For a darker, more uniform chocolate-brown patina: Use a low-concentration oxidizing agent during pre-patination, and control the humidity at 70–75% to adjust the oxide crystal structure
◆ For a lighter, terracotta-colored patina: Reduce the pre-patination time to 5–7 days, and use a mild rust accelerator to slow down the oxidation rate
All modified patinas will retain the self-healing ability, as the core alloy-driven oxidation mechanism remains unchanged
Key Limitation
It is not recommended to use non-breathable coatings (such as epoxy or acrylic paint) to modify the patina, as this will block the steel's contact with oxygen and moisture, disabling the self-healing function and causing localized corrosion under the coating
