For steel almirahs, lockers, cabinets, electrical panels, and sheet metal fabricated parts, an 8-tank pretreatment process is commonly used before powder coating to achieve good adhesion and corrosion resistance.
* Recommended Chemicals for MS Almirahs.
Tank 1 – Degreasing
Alkaline powder or liquid degreaser
Concentration: 20–50 g/L (supplier dependent)
Temperature: Ambient to 60°C
Tank 3 – Pickling
Hydrochloric Acid (HCl): 5–10%
Corrosion inhibitor added to reduce metal attack
OR
Sulfuric Acid (H₂SO₄): 5–15%
Tank 5 – Phosphating
For almirahs and sheet metal:
Iron Phosphate
Economical
Suitable for indoor furniture
Zinc Phosphate
Better corrosion resistance
Preferred for premium products
Tank 7 – Passivation
Chrome-free passivation is widely preferred today.
Improves salt spray resistance and paint adhesion.
Tank 8 – DM Water
Conductivity typically below 50 µS/cm (many plants target even lower values).
Prevents staining and improves coating quality.
