Wood surface requires .......... coats of plastering.
Surface Finishes: Choosing the Right Coat for the Right Material
Different construction materials require different types of surface finishes. The choice depends on the material's properties, such as its porosity, texture, and tendency to expand or contract. Plastering is a finish designed for masonry surfaces, while wood requires a different approach.
📝 Detailed Analysis of the Options
(a), (b), and (c)
These options are incorrect because plastering is fundamentally incompatible with wood. Plaster is a rigid, brittle material made from cement, lime, or gypsum. Wood, on the other hand, is a flexible material that expands and contracts with changes in temperature and humidity. Applying a rigid coat of plaster to a flexible wood surface would cause the plaster to crack and flake off as the wood moves. Therefore, wood is never plastered.
(d) None of these
This is the correct answer. Plastering is not a suitable finish for wood surfaces. Instead, wood is treated with finishes that are flexible and can protect it from moisture while enhancing its natural appearance. These finishes include:
- Paint: Provides a protective, opaque layer.
- Varnish/Polish: Provides a protective, transparent or semi-transparent layer that showcases the wood grain.
📊 Plastering vs. Wood Finishes
| Feature | Plastering | Paint / Polish |
|---|---|---|
| Purpose | To provide a smooth, level surface on rough masonry. | To protect from moisture and UV, and enhance appearance. |
| Suitable Surface | Brick, stone, concrete block walls. | Wood, metal, drywall. |
| Key Property | Rigid and hard. | Flexible and adherent. |
💡 Study Tips
- Plaster for Walls, Paint for Wood: This is a fundamental concept. Plaster covers imperfections on rigid surfaces like brick walls. Paint protects and decorates flexible surfaces like wood.
- Think Flexibility: Wood moves. Its finish must be able to move with it. Plaster can't move, so it cracks.
- Different Jobs, Different Tools: Remember that plastering and painting are entirely different trades using different materials for different purposes.