Advanced Plastering Techniques

MODULE 2-Advanced Plastering Techniques

This module covers professional plastering methods used in high-quality finishes for walls and ceilings. Learners will master mixing, application, and finishing techniques for different plaster types, ensuring smooth, durable surfaces.

1. Applying Finishing Plasters (Multi-Finish, Board Finish)

Finishing plasters provide the final smooth layer before painting or decorating.

Multi-Finish Plaster

• Uses: Versatile plaster for most backgrounds (plasterboard, bonding coat, sand/cement).

• Mix Ratio: ~2:1 (plaster to water) for creamy consistency.

• Application:

• Apply in two thin coats (1st coat scratched for key, 2nd coat smoothed).

• Trowel technique: Use firm pressure in arcs for even spread.

• Drying Time: 1–2 hours (depends on thickness and room conditions).

Board Finish Plaster

• Uses: Specifically for plasterboard surfaces (not for high suction backgrounds).

• Mix Ratio: Slightly thicker than Multi-Finish.

• Key Tip:

• Apply in one pass (no need for scratching, as plasterboard has low suction).

• Polish with a damp sponge trowel for ultra-smooth finish.

2. Floating Coats (Sand/Cement, Bonding Coats)

Floating coats create a level base before finishing plaster.

Sand & Cement Float

• Mix Ratio: 4:1 (sand to cement) + plasticizer for workability.

• Application:

• Apply 8–10mm thick with a steel trowel.

• Scratch while wet (using a devil float) for better adhesion of finish coat.

• Uses: High-suction backgrounds (brick, blockwork).

Bonding Coat (Gypsum-Based)

• Uses: For low-suction surfaces (e.g., concrete, dense blocks).

• Mix Ratio: Pre-mixed (just add water).

• Key Features:

• Quick-setting (30–45 mins working time).

• Must be covered with finishing plaster (not left exposed).

3. Skimming Techniques for Smooth Surfaces

Skimming is the final thin layer (2–3mm) for a polished finish.

Step-by-Step Skimming Process

1. Preparation:

• Dampen the surface (prevents rapid suction).

• Ensure floating coat is fully set but not too dry.

2. First Coat (Butter Coat):

• Apply evenly with a plastering trowel, covering the entire area.

• Scratch lightly with a notched trowel for a key (if needed).

3. Second Coat (Top Coat):

• Apply within 15–20 mins (while first coat is still workable).

• Use a water spray to keep edges workable.

4. Troweling & Polishing:

• First trowel: Smooth out ridges with firm pressure.

• Second trowel (after slight stiffening): Refine with a clean, slightly wet trowel.

• Final polish: Use a sponge or plastic trowel for glass-like finish.

Pro Tips for Perfect Skim:

Conclusion

Mastering these techniques ensures professional-grade plastering for both domestic and commercial projects. Practice is key—speed and precision improve with experience.