Foundation, Concrete and Earthquake Engineering

Preparation of Paints

Paints forms a thin film on drying on the painted surface which is applied in the from of liquid on timber, metal, brick or other materials. The paint film provides a protection or decoration or both to applied surface.

In most case white lead oil paint forms the basis of all the paints of light or bright colors. The base which is usually white lead is ground in linseed oil to the consistency of paste. Alternatively the base may be obtained in the form of the paste directly form the market.

The base in the state of stiff paste is then softened or " broken up'' by adding linseed oil in a small quantity at a time and then stirring the paste with wooden paddle. If a colored paint is desired the proper coloring pigment is ground very fine and mixed with linseed oil to the consistency of paste separately. Driers, if used should also be separately ground in linseed oil and the paste mixture of the three i.e. the base, the coloring pigment and the drier, is further thinned in to the consistency of cream by adding more linseed oil and stirring it well. The mixture is then strained through a fine canvas or a fine sieve. The paint is thinned to the desired consistency by the addition of oil or turpentine or both, just before it is to be used.

The paint thus prepared, should be used and consumed at the earliest. If the prepared paint has to be kept unused for some time, it should be covered with a film of water to protect it from drying or shrinking. Ready-mixed paints of varying composition and color are now produced by many manufactureres all over the world. Ready-mixed paints are generally too thick for direct application and as such they are thinned to desired consistency by adding suitable thinners and by stirring it well.

No comments:

Post a Comment