Some of the important points to be noted before we take up the discussion of process of painting are mentioned below:
(1) Brushes: It is necessary to have good brushes for painting. The brushes should be composed of bristles and not of horse hairs. The bristle brushes are elastic and possess good paint-holding capacity. The bristles are split at ends and in the respect, they can be distinguished from horse hairs.
It is preferable to use a round brush in printing. The new brushes should be soaked in water upto level of bristles for a period of about two hours and then they should be allowed to try for a period of about one hour. During painting, the brush should be immersed in paint upto about one-third length of the bristle and the excess paint in the brush is removed by gently pressing the bristles against the inside surface of the pot. After the work is over, the brushes should be cleaned at once with kerosene oil.
(2) Paints: The ready-mixed paints of different make and various brand are available in the market. They are available in different tints and can be applied in the same form as received. The ready-mixed paints are normally expensive and they are to be used soon after opening the sealed container because of the fact that volatisation of the vehicle and solvent will take place when exposed to the atmospheric oxygen. If the ready-mixed paint is kept exposed to air for along duration, the sclidification of the base and the pigment occurs.
The procedure for preparing paint from stiff paint is as follows:
(i) The sufficient stiff paint is taken in a pot. The remaining stiff paint is to be covered or left with a layer of linseed oil.
(ii) The linseed oil which may either be raw or boiled or pale is then mixed with stiff paint by a stick.
(iii) The other ingredients of paint are then added.
(iv) If a colour is required, suitable pigment is added and thoroughly mixed.
(v) A second pot is taken and
The term hard stopping is used when instead of ordinary putty, an admixture of one-third whit lead and two-third ordinary putty, is filled in holes, cracks, etc. it is adopted for superior work.
(5) Coats: The paint is usually when instead of ordinary putty, an a mixture of one-third white lead and two-third ordinary putty, is filled in holes, cracks, etc. it is adopted for superior work.
The priming coat creates a layer or film which provides adhesion of the paint with the surface. It is also protects the surface from weathering actions. The suitable material for priming coat should be used, depending on the nature of surface to be painted. The under coat serves to provide foundation or support to the finishing coat. The surface is made even and all irregularities of the surfaces are removed by this coat.
The finishing coat or coats are then applied as per requirements.
(6) Spray painting: Instead of the ordinary brushes, a spraying pistol may be used for painting work. The pistol works under compressed air and the paint thrown through the pistol on the surface forms a thin uniform film or layer of paint on the surface. The spray painting is superior to painting by brushes.