The essential ingredients of paints are:
Base
Vehicles
Pigment
Drier/ accelerator
Thinner
Base: It is a principal constituent of paint. It also possesses the binding properties of the finely divided material. It is opaque (untransparent) in nature. Commonly used bases for paints are white lead, red lead, zinc oxide, iron oxide, titanium white, aluminum powder and lithophone. A lead paint is suitable for painting of iron and steel works, as it sticks to them well. However it is affected by atmosphere action and hence should not be used as final coat. While zinc forms good base but is costly.
Lithophone, which is a mixture of zinc sulphate and barytes, is cheap. It gives good appearance but is affected by day light. Hence it is used for interior works only.
Lithophone, which is a mixture of zinc sulphate and barytes, is cheap. It gives good appearance but is affected by day light. Hence it is used for interior works only.
Vehicles: It helps to mix the various ingredient use in paint. The vehicles are the liquid substances which hold the ingredients of a paint in liquid suspension and allow them to be applied on the surface to be painted. Linseed oil, Tung oil and Nut oil are used as vehicles in paints. Of the above four oils, linseed oil is very commonly used vehicles. Boiling makes the oil thicker and darker. Linseed oil reacts with oxygen and hardens by forming a thin film.
Pigment: Pigments give required colour for paints. They are fine particles and have a reinforcing effect on thin film of the paint. The common pigments for different colours are:
Black- Lamp black, suit and charcoal black
Red- venedion red, red lead and Indian red
Brown- burned timber, raw and burned sienna
Green- chrome green, copper sulphate
Blue- Prussian blue and ultra marine
Yellow- ochre and chrome yellow
Black- Lamp black, suit and charcoal black
Red- venedion red, red lead and Indian red
Brown- burned timber, raw and burned sienna
Green- chrome green, copper sulphate
Blue- Prussian blue and ultra marine
Yellow- ochre and chrome yellow
Drier or accelerator: These are the compounds of metal like lead, manganese, cobalt. The function of a drier is to absorb oxygen from the air and supply it to the vehicle for hardening. The drier should not be added until the paint is about to be used. The excess drier is harmful because it destroys elasticity and causes flaking. It is Used about 8-10% in the paint.
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