Plaster defects: The local swelling (bulging) that appears on a finished plastered surface is termed

Introduction / Context:
Diagnosing plaster defects helps in prescribing correct repairs and preventing recurrence. Different defects have distinct causes and visual signatures. The term for localized swellings or bubbles forming after finishing is essential vocabulary for site supervision.

Given Data / Assumptions:

• A finished plaster surface shows small bulges or raised patches.
• Defects may arise from workmanship, materials, or substrate conditions.
• We distinguish between cracks, blisters, crazing, and other issues.

Concept / Approach:
“Blistering” describes the local swelling of plaster, often caused by improper troweling during setting, trapped air, over-rich fat lime, contamination, or lack of suction control on very smooth backgrounds. In contrast, “cracking” is the formation of fractures due to shrinkage or movement; “crazing” is a network of fine hairline cracks; “dubbing” is leveling out irregularities before final plaster; “hacking” is roughening the background to improve bond.

Step-by-Step Solution:
Identify the symptom: localized bulges or bubbles after finishing → blistering.Eliminate other terms: cracking (fractures), crazing (mesh of fine cracks), dubbing (pre-leveling), hacking (surface preparation).Therefore, the correct term is “Blistering”.

Verification / Alternative check:
Repair guides recommend cutting out blisters back to sound substrate, re-keying, and refilling with suitable plaster, confirming that the phenomenon is distinct from cracking or crazing.

Why Other Options Are Wrong:
Cracking/Crazing refer to fissures, not swellings.Dubbing is a preparatory operation, not a defect.Hacking is a roughening process, not a finished-surface issue.

Common Pitfalls:
Over-troweling or polishing too early; inadequate suction control; using contaminated water or salts that cause surface reactions.

Final Answer:
Blistering.