Common Problem Concrete Wall
Algae& Fungus Growth
Cause:
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High humidity,rainfall and sunlight.
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Dirt accumulation on surface which provide nutrient to algae or fungus and easy retention of algae spores.
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Insufficient or inappropriate fungicide or algaecide in the paint.
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Use of interior paint for exterior surface.
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Prevention / Remedy:
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High-pressure washing or manual scrubbing of all affected area.
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Treat surface with anti-algae wash.
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Wash again to remove any residue and allow to dry thoroughly. Make good the defects before applying exterior acrylic finish.
Peeling & Flaking
Cause:
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Poor surface preparation or unstable plasters.
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Wrong choice of primeror not using any alkaliresistant sealer.
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Moisture seepage on the wall as a resultof capillary
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pressure.
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Prevention / Remedy:
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Where appropriate, use high-pressure water blasting to remove all unstable substrate.
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Prime surface with
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penetrative solvent primer to further stabilizes the base.For non- ferrous metals such as aluminium, zinc coated (galvanized)and stainlesssteel, treat surface with acoat of KCC Polyetch 100 etching primer.
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Water seepage should be repaired and walls allowed to dry before painting with a desire paint system.
Efflorescence
Cause:
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Migration of water-soluble salts from cement / sand mixture to the surface often facilitated by moisture drying process.
Prevention / Remedy:
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Avoid painting on wall when moisture content is above 10% ( measure by portimeter).
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Stop all moisture seepage.
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Remove the affected paint film and depositing salts by high- pressure washing.
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Allow wall to dry thoroughly and repaint with suitable paint system.
Blistering
Cause:
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Moisture drawn through the wall and trapped in the paint-wall interface.
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use of water impermeable coating while the wall is still wet.
Prevention / Remedy:
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Avoid painting on wall when moisture content is above 10% ( measure by porttimeter).
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Stop all moisture seepage.
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Remove the affected paint film and depositing salts by high- pressure washing.
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Allow wall to dry thoroughly and repaint with suitable paint system.
Chalking
Cause:
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Disintegration of binders not resistant to weathering and UV attack.
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Adulteration of paint (addition of foreign material or mixing of lower grade paint)
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use of interior paint for exterior surface.
Prevention / Remedy:
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Ensure the use of the weather resistance paint.
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for previously adulterated paint. ensure it is thoroughly removed by high-pressure washing. all wall to dry and apply with the correct paint.
Discoloration
Cause:
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Sensitive pigments deteriorate / erode on exposure to heat / sunlight or highly corrosive environment.
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Migration of water-soluble salts from cement / sand mixture to the surface, oozing out of oil / wood from timber grain and contamination of rust from metal can also discolor the paint.
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Alkali attack onto sensitive pigment.
Prevention / Remedy:
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Avoid reds, oranges, yellow, violets, pink color for external. However higher prices have to be paid for paints that use these better grade pigments.
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Water seepage shall be repaired. Once the substrate is sufficiently dry, repainting is carried out with a cement compatible solvent base sealer.
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Timber surface shall be primed with primer while for metal, the remedy is to employ good surface preparation and repair.