Things You'll Need:
- TSP (Tri-sodium Phosphate)
- Plain water
- Invisible (colorless) spray paint
- A dry non-abrasive scrubber
- Sponges
- Soft wash cloths
- Waterproof interior/exterior enamel paint
- A soft brush or a sponge to spread the solution on the wall
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Step 1
Scrub the wall surface with a brush or damp cloth to ensure that the wall has an even finish. Plaster walls tend to be a little uneven on the surface, which makes them difficult to clean.
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Step 2
Use a strong solution of TSP (Tri-sodium Phosphate) mixed with water with a ratio of 1:15 (TSP: Water). You can also try using a non-phosphate substitute for water.
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Step 3
Use a dry non-abrasive scrubber, a soft brush or a sponge to rub the solution on the area of the wall which requires cleaning. The water will be absorbed by the wall surface but the Tri-sodium Phosphate action will disintegrate dirt and stains.
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Step 4
Allow the cleaned area to dry for few hours. Use a mild solution of TSP and scrub the surface again with a soft cloth to remove loose dirt off the wall. Do not scrape off or you will end up spoiling the wall surface.
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Step 5
Use an invisible (colorless) spray paint to fill out the porous surface of the wall to keep the wall surface clean.












