Which of the following defects is due to poor bonding between coats of plaster? 

Explanation:

• Flaking is a defect in plastering where small patches or layers of plaster peel away from the surface.

• This usually occurs due to poor bonding between successive coats of plaster or between the plaster and the base surface.

• It can also result from insufficient curing, use of low-quality materials, or application on a dusty or oily surface.

• The surface becomes uneven and may require complete reapplication.

Additional Information Blistering

• Formation of small, localized swellings or bubbles on the plastered surface.

• Caused by entrapped air or moisture under the top coat, not due to poor bonding between coats.

Staining

• Occurs as discolored patches on the surface of plaster.

• Generally caused by rusting of metal elements, salt efflorescence, or water seepage, not by bonding failure.

Popping

• Appearance of conical fragments or lumps on the plaster surface, typically due to the presence of unslaked lime or other impurities that expand after plastering.

• Not related to inter-coat bonding.