FAQs

The following factors may be the possible cause of cracks in plasterwork: earth movement and settling; fast curing due to lack of moisture; a too strong plaster mix, or a weak plaster mix; poor sand quality. Cracks will re-open after painting and cause paint systems to fail, and moisture ingress may cause damage to the substrate. Open, clean and fill all plaster cracks as follows:

• Hair Cracks (-0.2mm): Remove dust and debris. Brush DULUX RAINSHIELD well into the cracks with an old small brush to fill and bridge the cracks.
• Plaster cracks (+0.2mm and -2mm) are to be raked out with a scraper blade. Remove dust and debris. Brush DULUX RAINSHIELD well into the cracks with an old brush to fill and bridge the cracks. Repeat if necessary to fill in the cracks completely.
• Walls with extensive "map-crazed" cracks: Open, clean and fill all cracks wider than 2mm according to instructions above. After all cracks have been opened, cleaned and filled, coat the entire wall from corner to corner with DULUX RAINSHIELD (exterior), or DULUX DURAPLAST (interior). Alternatively, apply plaster/adhesive slurry from corner to corner.
• Large structural cracks (+2mm), and holes must be opened out with a carborundum disk in a V-shape to 3mm or larger. The cleaned cracks should be wetted, and then filled with a damp cement/sand mortar with a ratio of 1:4. The in-fill mortar should be properly compacted into the cracks. Apply DULUX RAINSHIELD well into and around filled area to provide a flexible bridge.
• Movement cracks at abutting walls. Cut open and clean away dust and debris. Fill with flexible filler such as single pack polyurethane sealer plus backing cord. In boundary walls, treat cracks with sealer and backing cord on both sides.