How long should new cement plaster cure before whitewashing?

The surface should be allowed to cure for at least 10 days and be surface-dry before applying wash (Clause 4.2.1.1).

How do you prepare a colour-wash?

Prepare a whitewash solution first, then mix the required pigment with water to form a thin paste and add it to the whitewash, stirring continuously until a uniform colour is achieved (Clause 5.3).

How many coats of whitewash are needed for new work?

Usually one priming coat followed by two or more finishing coats until the surface presents a solid white appearance (Clause 6.1).

How do you prepare an old, previously painted surface for whitewashing?

The old paint must be thoroughly scraped off, and the surface cleaned, repaired if necessary, and allowed to dry completely before applying the new wash (Clause 4.2.2).

IS 6278

: 1971

Code of Practice for Whitewashing and Colour-washing

CurrentSpecializedCode of PracticeArchitectural · Flooring, Wall Finishing and Roofing

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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

Quick Reference Values

Minimum curing time for new lime plaster before wash6 weeks

Minimum curing time for new cement plaster before wash10 days

Unhydrated lime for 100 sq m whitewash (per coat)10 kg

Gum to be added per 10 kg of lime200 g

Minimum drying time between coats24 hours

Copper sulphate added to 10 kg lime for sanitation30 g

Practical Notes

Straining the lime solution through a clean coarse cloth is critical to remove unslaked particles and ensure a smooth, uniform finish.

For colour-washing, it's essential to prepare the entire quantity of tinted wash required for one room at a single time to avoid patchiness and colour variation.

Adding an adhesive, such as gum arabic or a modern equivalent, significantly improves the durability and reduces the chalking (rub-off) of the finished surface.