IS 3140:1965 is the Indian Standard (BIS) for painting asbestos cement building products. This code of practice covers the recommended methods and precautions for painting asbestos cement building products. It emphasizes the need for alkali-resistant primers due to the high alkalinity of asbestos cement surfaces.
Code of practice for painting asbestos cement building products
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Weathering Period for New Sheets | Allow at least one month of exposure to weather before painting. | For unprimed sheets, a weathering period of 4-6 weeks is recommended to reduce alkalinity. Not required for factory-primed sheets. | AS/NZS 2311:2017 |
| Treatment for Alkalinity | Apply a solution of zinc sulphate (1 kg in 5L water) or 1:25 sulphuric acid, then wash and dry. | Acid etching is not generally recommended. Instead, use a high-quality, alkali-resistant primer (e.g., 100% acrylic). | ASTM D7897-15 |
| Removal of Efflorescence | Remove by dry brushing with a stiff bristle (not wire) brush. | Remove by dry-brushing, scraping, or washing. The surface must be allowed to dry thoroughly if washed. | BS 6150:2020 |
| Recommended Primer Type | An alkali-resistant primer is specified for oil-based paints. | A high-quality 100% acrylic or acrylic latex primer specifically designed for high pH substrates is recommended. | ASTM D7897-15 |
| Application Method | Application by brushing is the primary method described. | Application can be by brush, roller, or airless spray, according to the paint manufacturer's instructions. | BS 6150:2020 |
| Surface Preparation for Old Paint | Remove all loose paint by scraping and wire brushing. Wash and dry. | Scrape and sand failing paint. (Note: Wire brushing or sanding of asbestos-containing material is now illegal in many jurisdictions without strict controls). | General practice in BS 6150 / ASTM D7897 (with modern safety caveats) |