Common Issues with Latex Paint

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1. Blistering: Main causes include improper base treatment and excessively thick coats, particularly when using blockboard as the base. Preventive measures involve stirring the paint thoroughly before use and controlling its viscosity. Applying a coat of 107 glue on the putty base before painting can help. For rework, remove all blistered and peeled material, apply 107 glue, and then repair.

2. Alkali Efflorescence and Powdering: Primarily caused by construction on damp, undried surfaces, absence of a sealing primer, or overly diluted paint. If efflorescence occurs, redo the work: remove existing paint, allow the base to dry completely, and apply a sealing primer before repainting. For new walls, ensure the topcoat viscosity is appropriate; white walls require slightly thicker consistency.

3. Sagging: Usually due to low paint viscosity or overly thick application. Adjust paint viscosity during construction, avoid excessive water, and use a brush with frequent dipping, minimal load, and smooth strokes to prevent sagging. If sagging occurs, wait for the film to dry, sand with fine sandpaper, clean the surface, and apply another topcoat.

4. Poor Hiding/Transparency: Results from overly diluted paint, insufficient coats, or poor-quality materials. Choose products with high solid content and strong coverage. If transparency is observed, increase the number of topcoat applications to meet wall coverage standards.

5. Unsmooth Coating: Caused by impurities in the paint, overly thick consistency, or inferior paint quality. Use reputable brands with good leveling properties. Filter the paint before the final coat. If the coating is uneven, sand smooth with fine sandpaper and reapply a topcoat.

6. Cracking: Low construction temperatures preventing proper film formation; improper base treatment (e.g., wall cracks leading to film cracks); applying a second coat before the first dries completely, causing differential drying rates; cracking of cement putty base leading to film cracks.

7. Peeling: Low construction temperatures causing incomplete film formation and cracking, which leads to peeling when wet; loose or oily bases reducing adhesion; low-strength putty applied before drying; overly smooth bases impairing adhesion.
   Prevention: Inspect walls for leaks before construction and address them promptly. Use durable, waterproof elastic putty for pretreatment before standard painting. Ensure the wall is thoroughly cleaned.

8. Discoloration and Fading: High wall temperatures or prolonged sunlight exposure; crystallization of water-soluble salts on the surface; high alkalinity in walls damaging weak alkali-resistant pigments or resins.
   Note: Avoid using latex paint and polyurethane paint simultaneously. Apply latex paint two days after oil-based paint, or wait until the latex paint is fully dry (7 days at 25°C) before applying oil-based paint.