Using gypsum powder on walls, often referred to as gypsum punning or plastering, is a method to achieve smooth, finished surfaces for painting or wallpapering. This process is typically applied over base plaster (like cement sand plaster) or directly onto smooth blockwork or concrete surfaces.
What is Gypsum Punning?
Gypsum punning involves applying a thin layer of gypsum-based material to walls. The primary goal is to create a uniform, level, and exceptionally smooth finish that is ready for final decoration without the need for extensive curing or multiple leveling coats required by traditional methods.
Steps for Using Gypsum Powder on Walls
Based on standard practices and the insights from the reference regarding "Wall Punning":
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Surface Preparation:
- Ensure the wall surface is clean, free from dust, oil, and loose particles.
- Dampen the surface slightly (not soaking wet) to improve adhesion.
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Mixing the Gypsum Plaster:
- Mix the gypsum powder with clean water according to the manufacturer's instructions.
- It's crucial to add the powder to the water gradually while mixing continuously until a smooth, lump-free paste consistency is achieved.
- Prepare only as much material as can be used within its working time (gypsum sets relatively quickly).
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Application:
- Apply the mixed gypsum plaster onto the wall surface using a trowel or putty knife.
- Spread the material evenly, working from bottom to top or in sections.
- Use a straight edge or level to ensure the surface is flat and true.
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Smoothing and Finishing:
- While the plaster is still workable but starting to set, use a steel trowel to smooth the surface.
- For a finer finish, a second, very thin coat might be applied and smoothed.
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Drying:
- Allow the applied gypsum plaster to dry completely. The drying time depends on the thickness of the application, temperature, and humidity.
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Sandpapering (as per Reference):
- After drying the surface should be sandpapered to give a smooth surface. This step is highlighted in the reference as key to achieving the desired finish.
- Use fine-grit sandpaper or a sanding block to lightly sand the dried gypsum surface, removing any minor imperfections, trowel marks, or roughness.
Benefits of Using Gypsum Punning
Utilizing gypsum powder for wall finishing offers several advantages:
- Smooth Finish: Provides a highly smooth and level surface ideal for painting or wallpapering.
- Time-Saving: As mentioned in the reference: "In this way you save time for curing of cement sand plaster. And you also save time for leveling coat of pop." Gypsum plaster sets and dries relatively quickly and often requires only one coat, reducing overall project time compared to traditional methods.
- Reduced Shrinkage Cracking: Gypsum plaster generally exhibits less shrinkage compared to cement-based plasters, leading to fewer cracks.
- Improved Aesthetics: Creates a clean, white surface that can enhance paint colors.
Comparison with Traditional Methods
| Feature | Gypsum Punning | Cement Sand Plastering + POP Leveling |
|---|---|---|
| Curing Time | Minimal to None | Requires several days of water curing |
| Setting Time | Faster | Slower |
| Application | Often a single coat for smoothing | Base coat + leveling coat(s) |
| Final Finish | Very smooth, requires sandpapering after drying | Requires POP or putty for smoothness |
| Time Saved | Significant, as noted in the reference | More time consuming |
Practical Tips
- Always follow the manufacturer's instructions for mixing ratios and application thickness.
- Work in manageable sections, especially in warm conditions where the plaster can set quickly.
- Ensure good ventilation during drying.
By following these steps, particularly incorporating the crucial sandpapering step after drying as indicated by the reference, you can effectively use gypsum powder to achieve a smooth, finished wall surface efficiently.
