IS 2524:2000 (Part 1) is the Indian Standard (BIS) for the painting of nonferrous metals in buildings, part 1: pretreatment. This code covers the essential pretreatment processes required for non-ferrous metals like aluminum, zinc (galvanized iron), copper, and lead before painting in buildings. It details cleaning, degreasing, mechanical roughening, and chemical conversion methods (such as wash primers) to ensure proper adhesion and long-term durability of the paint film.
Code of practice for the painting of nonferrous metals in buildings, Part 1: Pretreatment
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Aluminium Etch Primer Acid | Phosphoric acid (sp gr 1.75) 20 to 25 ml in 1 litre of water. | Typically a two-component system where the acidic component contains 8-15% phosphoric acid by weight along with vinyl butyral resin. | SSPC Paint 27 |
| Alkaline Chromate Treatment Temp. (Aluminium) | 90-100°C for 5 minutes. | Common chromate conversion coatings are applied at or near ambient temperature (20-40°C) for 1-5 minutes. | ASTM B449 (Industry Practice) |
| Pretreatment for Zinc (Mordant Wash) | Prescribes a specific single-component formula containing phosphoric acid and copper carbonate ('T-Wash'). | Recommends a two-component 'wash primer' system (e.g., conforming to SSPC Paint 27) or phosphating as per other standards. | ASTM D2092 |
| Anodizing as Paint Base (Aluminium) | Recommends anodizing as per IS 1868, but does not specify a thickness or sealing requirement for painting. | Recommends an unsealed anodic film with a thickness of 5 to 8 micrometers (µm) for optimal paint adhesion. | ASTM D1730 |
| Surface Cleanliness Standard | Qualitative: 'free from oil, grease, welding fluxes and other foreign matter'. | Quantitative: Specifies cleanliness grades by referencing other standards, e.g., 'Sa 2½' from ISO 8501-1 for abrasive blasting. | ISO 12944-4 |
| Phosphating for Zinc | Recommends 'light' phosphate coatings without specifying coating weight. | Specifies coating mass per unit area, e.g., typically 1.1 to 11 g/m² depending on the class. | ISO 9717 |