It is used for common walls and ceilings, "especially where, for sanitary reasons, a frequent fresh application is considered preferable to any coating which would last better. It readily comes off when rubbed, will not stand rain, nor adhere well to very smooth or non-porous surfaces. It is cheap, and where used for sanitary reasons should be made up of hot lime and applied at once, under which conditions it also adheres better." 1
Whitewash is improved by adding 1 lb. of pure tallow (free from salt) to every bushel of lime.
The process is generally described as lime whiting.
The following is a method recommended for making whitewash for outside work.
"Take a clean water-tight barrel, and put into it half a bushel of lime. Slake it by pouring water over it boiling hot, and in sufficient quantity to cover it 5 inches deep, and stir it briskly till thoroughly slaked. When the slaking has been effected, dissolve it in water, and add 2 lb. sulphate of zinc and 1 of common salt; these will cause the wash to harden, and prevent its cracking." 2
Common Colouring is prepared by adding earthy pigments to the mixtures used for lime whiting.
The following proportions 2 may be used per bushel of lime; more or less according to the tint required : -
4 to 6 lbs. of ochre.
6 to 8 lbs. umber; 2 lbs. Indian red; 2 lbs. lampblack.
6 to 8 lbs. raw umber, and 3 or 4 lbs. lampblack.
Whiting is made by reducing pure white chalk to a fine powder.
It is mixed with water and size, and used for whitening ceilings and inside walls. It will not stand the weather.
"The best method of mixing it is in the proportion of 6 lbs. whiting to 1 quart of double size (see p. 449), the whiting to be first covered with cold water for six hours, then mixed with the size and left in a cold place till it becomes like jelly, in which condition it is ready to dilute with water, and use."
"It will take 1 lb. jelly to every 6 superficial yards."1
Whiting is made in three qualities - common, town, and gilders. It is sold by weight in casks containing from 2 to 10 cwts., in sacks containing 2 cwts., in firkins (very small casks), in bulk, and in small balls.
Distemper is the name for all colouring mixed with water and size.
White Distemper is a mixture of whiting and size.
The best way of mixing is as follows : - Take 6 lbs. of the best whiting and soak it in soft water sufficient to cover it for several hours. Pour off the water, and stir the whiting into a smooth paste, strain the material, and add 1 quart of size in the state of weak jelly; mix carefully, not breaking the lumps of jelly, then strain through muslin before using; leave in a cold place, and the material will "become a jelly, which is diluted with water when required for use.
Sometimes about half a tablespoonful of blue black is mixed in before the size is added.
It is sometimes directed that the size should be used hot, but in that case it does not work so smoothly as when used in the condition of cold jelly, but on the contrary drags and becomes crumpled, thus causing a rough surface.
When the white is required to be very bright and clean, potato starch is used instead of the size.
In mixing the tints the whiting is first prepared, then the colouring pigment, the latter being introduced sparingly, size is then added, and the mixture is strained.
The colours are classed as "Common," "Superior," and "Delicate," in the same way as described at page 422.
The quantity of materials required for plastering, rendering, etc., depends upon the nature of the materials used, the degree of roughness of the walls, and other circumstances. Information on this subject will be found in the Builders' Price-books, Hurst's Surveyor's Pocket-Book, etc. The following Table was carefully compiled from practical observation for Colonel Seddon's Notes on the Building Trades, etc. -