Painting Damp Walls
Paraffin, 11 litres
Benzoline, 9 litres
Pale resin, 6 kg.
Shake them in a vessel; when completely dissolved add 11 kg whiting and grind the whole mixture well. Keep the mixture airtight to prevent drying. Apply on damp walls as ordinary paint one or two coat according to dampness. It will dry hard. Paint can be applied on it.
Painting Cement Surfaces
The surface should be first treated with a wash of dilute white vitriol (zinc) sulphate or washing soda are also effective and then primed as for plaster work; or alternatively, use the proprietory cement paints.
Cement Paints
Cement paints are available which are water paints and can be applied to all cement or concrete surfaces and brickwork. These paints resist the penetration of moisture and have particular advantage for use over exterior walls of buildings or on floors. They are applied with distemper brushes. Cement paints are of two types, for general use and for use on water retaining structures. Either of these types may be admixed with silica sand when used on open texture walls. Cement paints are supplied as powder to be stirred into water just before use.
The surface to be painted should be cleaned of all dust, dirt, oil, grease or efflorescence and wetted before the application of the paint. Soap should not be used for cleaning. An interval of about 3 to 4 weeks or more should allowed between the curring of the concrete and painting. Generally two coats are sufficient for most purpose and an interval of not less than 24 hours should elapse between the two coats. About 5 litres of mixed paint is considered sufficient for 10 sq.m of smooth surface and 4 sq.m of very rough surface. Excessive thick coats are not recommended. As soon as after the paint has sufficiently hardened, the surface should be kept wet for about 3 days through a light spray of water applied serveral times a day.
Lamp Blacking : (For dark rooms and racquet courts) :
5 kg lamp black
3 kg dry white lead
6 litres boiled linseed oil
0.6 litres turpentine
Will cover about 80 sq.m of surface.
Coal Tarring
Add one kg of unslaked lime to five litres of tar and heat it till it beings to boil. Take off the fire and add slowly one part kerosene oil to four parts tar, or ¼ litre country spirit 4 litres of tar. Addition of the kerosene oil is often omitted ; lime is added to neutralize the free acid and to prevent the tar from running out in hot weather. Tar is also mixed with turpentine and linseed oil. The tar should be applied as hot as possible, the articles to be tarred should be dipped into tar. Not less than 5 kg of coal-tar should be used per 10 sq.m of surface tarred. If possible the iron should be heated to a red heat and then tar brushed over. Where Solignum or Creosote is to be applied, these should also be applied very hot.
Creosote is a product obtained by distilling tar and is largely used as an effective preservative for wood.
Solignum is an excellent preservative for wood timber is subjected to dry rot. It is made in serveral colours but brown is most generally used.
The wood to be painted must be clean and absolutely dry. Where two coats are specified each coat must be thoroughly dried before the next one is applied.
A once tarred surface cannot be painted well. After the tarred surface has been scrapped, two coats of good shellac knotting varnish should be applied before pointing.
Painting Brushes
The brushes should be of bristles and not horse hair. Bristles can be distinguished by the fact that each bristle is split at ends. A good brush should have springiness in the bristles.
The following sizes of brushes are generally used:
a. For dusting large flat surfaces, sizes 12 or 14.
b. For girder work, size 8.
c. For wood work, size 6.
d. For fine work, size 2 and 4.
A round brush is considered the best for painting.
New brushes should be placed in water for 2 to 3 hours, and then allowed to dry for one hour before use. When a brush is to used for another colour or is no longer required, it should be cleaned at once by dipping into kerosene when not in use.
