Plastering: The Crucial Bridge Between Masonry and Paint
Plastering creates a protective envelope over raw masonry, seals air gaps, and provides a perfectly flat, plumb surface for putty and paint. Poorly executed plastering results in visible waves under artificial cove lighting, hollow debonded patches, and map cracking.
Pre-Plastering Quality Checks
- Raking of Masonry Joints: Mortar joints between bricks must be raked to a depth of 10mm while fresh to provide a mechanical key for plaster bonding.
- Hacking Concrete Surfaces: Smooth RCC surfaces (column faces and slab bottoms) must be mechanically hacked to produce at least 30 to 40 indentations per square foot, followed by a bonding slurry coat of cement-polymer mix.
- GI Chicken Mesh at Joints: 200mm wide strips of galvanized chicken mesh must be nailed across every joint where brickwork meets concrete columns or beams to arrest differential thermal expansion cracks.
Post-Plastering Field Verification
- Straight Edge & Level Tube Check: Place a 3-meter aluminum straight edge along walls vertically and horizontally. The gap between the straight edge and the plastered surface must not exceed 2mm to 3mm at any point.
- Right Angle Corner (Try Square) Check: In rooms where wardrobes, kitchen counters, or tile corners meet, use a builder's right-angle try square. Corners must be exact 90-degree right angles to prevent wedge-shaped gaps behind modular cabinetry.
- The Tapping Test for Hollow Sound: Gently tap the plastered surface with a light wooden mallet or coin after 7 days of curing. A crisp click indicates solid adhesion; a dull, hollow "drumming" sound indicates debonded plaster that must be cut out and replastered.
- 7-Day Curing: Internal and external plaster must be water-cured 2 to 3 times daily for a minimum of 7 consecutive days to achieve proper surface tensile strength.