Plaster is thin, spread over large areas, and exposed to sun and wind while it sets — exactly the conditions that make cement shrink and crack. The cement you choose, and how you use it, decides whether the walls stay smooth.
Cement Choice for Plaster
| Cement | For plaster | Why |
|---|---|---|
| PPC | Best choice | Gentle setting, low heat, less shrinkage cracking, economical |
| OPC 43 | Good | Moderate setting and heat |
| OPC 53 | Avoid if possible | Fast setting and high heat raise crack risk |
Mix Ratios
| Plaster | Mix | Thickness |
|---|---|---|
| Internal walls | 1:6 | About 12 mm |
| External walls | 1:4 | 15 – 20 mm in two coats |
| Ceilings | 1:3 or 1:4 | About 6 mm |
Avoiding Plaster Cracks
- Dampen the wall before plastering so it does not suck water from the plaster.
- Fix mesh across junctions of walls with columns and beams.
- Do not over-enrich — 1:4 is not "better" than 1:6 inside.
- Control water — workable, not sloppy.
- Apply in thin coats; external plaster in two coats.
- Shade from direct sun in Hyderabad's summer afternoons.
- Cure for at least 7 days.
For AAC walls, use a bonding coat and keep plaster thin.
The Short Version
Plaster with PPC (or OPC 43), lean mixes, thin coats, damp walls, mesh at junctions and a week of curing. Save OPC 53 for structural concrete.
