1. Sandblasting / Shot blasting
Removes hot‑rolling oxide scale completely.
Creates a clean, slightly rough surface with many nucleation sites.
Greatly accelerates oxidation and patina growth.
Produces uniform, even color from the early stage.
This is the most widely used and effective method in engineering and architecture.
2. Pickling (chemical descaling)
Uses acid to remove scale and surface contaminants.
Provides a chemically clean surface for rapid, even rusting.
Patina starts earlier and develops more uniformly than the original hot‑rolled surface.
3. Mechanical roughening
Grinding, wire brushing, or other surface roughening methods.
Increases surface area and promotes faster oxide formation.
Faster than a smooth polished surface but less effective than sandblasting.
4. Artificial chemical patina acceleration treatment
Special chemical solutions sprayed onto the clean surface.
Simulates the effect of long‑term outdoor exposure.
Can form a mature, stable patina in days to weeks instead of 1–3 years.
Allows control of the final color tone (reddish brown, dark brown, etc.).
5. Flame cleaning / surface oxidation treatment
Briefly heats the surface to form a uniform initial oxide layer.
Promotes faster and more consistent patina development.
