Explain defects in painting
1 Answer

Following are the usual defects which are found in the painting work:

a. Blistering: This defect is caused by the water vapour which is trapped behind the painted surface. The formation of bubbles under the film of paint occurs in this defect. It may occur from various causes such as imperfect seasoning of timber, excess oil used in final coat, etc.

b. Bloom: In this defect, the formation of dull patches occurs on the finished polished surface. It is due to the defect in paint or bad ventilation.

c. Fading: The gradual loss of colour is known as fading and it is mainly due to the effect of sunlight on pigment of paint.

d. Flaking: A small portion of the painted surface is sometimes seen loose. It is known as flaking and is due to poor adhesion.

e. Flashing: Sometimes the glossy patches are seen on the painted surface. This is known as flashing and it is mainly due to poor workmanship, cheap paint or weather actions.

f. Grinning: When the final coat of paint has not sufficient opacity, the background is clearly seen. This is known as grinning.

g. Running: The paint runs back and leaves small areas of surface uncovered. This defect occurs when the surface to be painted is too smooth.

h. Sagging: When a vertical or inclined surface is too thickly painted, the defect of sagging occurs.

i. Saponification: The formation of soap patches on the painted surface is termed as the saponification and it is due to chemical action of alkalies.

j. Wrinkling: When a horizontal surface is too thickly painted, the defect of wrinkling becomes prominent.

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