Suitable for removing mature patina without damaging the SPA-H steel base, ideal for planters that need to restore the original steel color or reprocess the surface.
: Use fine quartz sand or steel grit for low-pressure sandblasting (SA2.5 grade) on the patina surface-this quickly strips off the dense oxide layer, exposing a clean, uniform fresh steel surface, and the effect is consistent on both flat and curved parts of the planter.
Wire brushing + sanding: For small-area patina removal (e.g., local touch-up), use a fine soft wire brush (avoid hard steel wire that scratches the steel) to scrub the patina, then polish with 240-400 grit sandpaper to smooth the surface; this method is manual and suitable for small-sized planters.
High-pressure water washing: Use high-pressure water (150-200 bar) with a mild neutral cleaning agent to rinse the patina-suitable for removing loose, immature patina (formed within 6 months), and less effective for fully mature, dense patina layers.
Suitable for removing thick, stubborn mature patina in a short time, and must be operated with protective measures to avoid steel surface corrosion and environmental pollution.
: Apply a professional neutral weathering steel rust remover on the patina surface, let it react for 10-20 minutes (follow the product instructions), then wipe off the dissolved patina with a soft cloth and rinse thoroughly with clean water; neutral formula will not corrode the SPA-H steel base or leave residues.
Acid-based rust remover (avoid for daily use): Diluted phosphoric acid or oxalic acid can dissolve patina quickly, but it will etch the steel surface, cause pitting corrosion, and destroy the alloy element distribution on the surface-leading to uneven re-rusting later; only use it for extreme cases and neutralize the surface with alkaline water immediately after removal.
: The bare SPA-H steel surface after patina removal is highly reactive and will start to form a new loose rust layer within a few hours of outdoor exposure; it is recommended to do subsequent treatment (e.g., spray outdoor fluorocarbon coating, apply accelerated patina agent) within 24 hours to avoid random re-rusting.
Avoid over-removal: Do not use excessive sandblasting pressure or corrosive chemicals for a long time-this will thin the steel plate and affect the structural strength of the planter, especially for thin-walled SPA-H planters (thickness <=3mm).
: If only removing patina from a small damaged area, ensure the post-treatment of the bare surface is consistent with the surrounding mature patina (e.g., apply a matching accelerated patina agent) to avoid obvious color differences after re-rusting.
The planter needs to be re-painted/coated to change the color and style;
The patina layer has local peeling, pitting corrosion or uneven color due to harsh environment (e.g., high-salt coastal area) and needs to be reprocessed for a uniform surface;
The planter is refurbished, moved or repurposed and requires a clean original steel surface for secondary processing.
