IS 6278:1971 is the Indian Standard (BIS) for whitewashing and colour-washing. This code of practice details the methods for applying whitewash and colour-wash to building surfaces. It covers material requirements, surface preparation for new and old work, preparation of the wash solutions, and application techniques to ensure a satisfactory finish.
Code of Practice for Whitewashing and Colour-washing
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Curing Time for New Plaster (before painting) | At least 6 months to ensure complete freedom from efflorescence. | Check moisture content is below a specified limit (e.g., <5% WME); typically 28 days for cement plaster, or 1 month per 5mm thickness for lime plaster. | BS 6150:2019 |
| Lime Preparation | Fat lime to be slaked on site for a minimum of 24 hours. | Use of pre-packaged hydrated lime. For heritage work, quicklime is slaked for a minimum of 3 months to form lime putty. | BS 6150:2019 (heritage practice) |
| Use of Additives for Hardening | Permits addition of common salt (Sodium Chloride) at approx. 20 N/m³ of lime. | Prohibits the addition of soluble salts like NaCl, as they are a primary cause of future efflorescence and potential substrate damage. | BS 6150:2019 / General Conservation Principles |
| Binder Additive | Recommends adding gum or a PVA-based adhesive (e.g., Fevicol) at a specified ratio. | Advises against site-mixing of non-specified binders. Recommends using proprietary, formulated limewash with integrated binders like casein or linseed oil. | DIN 18363:2019-09 |
| Number of Coats | Prescribed as 'ordinarily a three-coat work'. | Performance-based: 'Sufficient coats to achieve a solid, uniform finish', typically 2-4 coats depending on substrate and opacity. | AS/NZS 2311:2017 |
| Application Tool | Specifies brushes made from moonja grass or bristles. | Recommends soft, natural bristle brushes ('flat fitch'). May also permit spray application for certain formulations and large areas. | BS 6150:2019 |