What is White wash?

by Swati 12/10/2021

White wash:

It is a process of giving wash covering to the plastered or pointed surface.
In case of white washing a wash of slaked lime mixed with water is applied.
Sometimes other ingredients like gum, rice water, common salt etc are added to improve the properties of the lime.

Operations included in White wash:

The material required for white washing is fat lime or shell lime unslacked lime lumps are mixed with water and the mixture is thoroughly stirred with the help of bamboo.
The lime is allowed to get fully slaked for about 24 hrs.
After 24 hrs, it is stirred up with a pole and additional water is added until it attains the consistency of thin cream.
This mixture is then screened through a clean cloth.
Clean gum is dissolved in hot water at rate of 4 kg/m of thin cream.
The dissolved gum is added to the slaked lime solution.
Sometimes alum, common salt or rice water are used in place of gum. To prevent the glare effect due to white wash sometimes copper sulphate at the rate of 4 kg/m of thin cream is added.
Gum or rice water are used to improve adhesive properties of white wash.

Before applying it, the surface to be white washed should be made thoroughly day.
If the surface is new, it should be thoroughly cleaned, brushed and made free from mortar
dropping or any other loose materials.
If the surface is very smooth, it will not stick to it and therefore, the surface should be rubbed with sand paper to ensure proper adhesion of white wash.
In case of white washing the old surface again, all loose materials and scales should be scrapped off.
The old loose white wash is removed by rubbing with sand paper.
All holes in the wall, irregularities of surface should be filled with lime putty well in advance, so that the surface is dry before white washing.
If there are oil or grease spot on the surface, they should be rubbed with sand paper and should be given a coat of mixture of rice water and sand, so that the it can stick to the surface.
If the surface is discoloured because of smoke, the surface should be washed with wood ash and water.

After preparing the surface it is applied in one coat, two coat or three coat.
In case of new surfaces three coats of it are required and for old surfaces one or two coats of it are sufficient.
The white washing is done with the help of a jute brush.
For each coat one stroke is given from top to bottom and the other from bottom to top over the 1st stroke and one stroke from the right and other from left over the first stroke.
Each successive stroke of brush should slightly overlap the preceding stroke.
If only one or two strokes of it are to be applied the last coat should be applied with horizontal strokes of the brush.
Each coat should be allowed to dry before applying the next coat.
The finished dry surface of it should be smooth and even and it should not come off readily on fingers when rubbed.

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