| New plaster | Dryness, laitance, polished areas, cracks and the plaster manufacturer’s guidance. | Allow adequate drying, remove dust and use the first coat specified for the chosen system. | Vinyl rich or impermeable finishes before the background is ready. |
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| Previously painted walls | Adhesion, sheen, contamination, filling, stains and weak previous layers. | Clean as required, abrade where needed, repair, spot prime and apply compatible finish coats. | Treating every old surface as ready because it looks intact from a distance. |
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| Interior timber and MDF | Bare edges, knots, resin, movement, previous coating and frequent contact areas. | Degrease, abrade, fill selectively and prime bare or vulnerable areas with the appropriate product. | Using wall paint or relying on a finish coat to seal porous MDF edges. |
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| Exterior timber | Moisture, open joints, end grain, putty, decay and the depth of existing failure. | Remove unsound coating, repair only sound timber, prime exposed areas and respect drying conditions. | Sealing damp or decayed timber beneath a fresh film. |
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| Metalwork | Metal type, corrosion, mill scale, previous system and contact with dissimilar metals. | Remove loose corrosion, clean thoroughly and use a compatible anticorrosive primer where required. | Applying a decorative topcoat directly over active rust. |
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| Masonry and render | Cracks, salts, friability, water paths, algae and previous coating type. | Resolve defects within scope, clean, allow to dry and prime or stabilise only where the system requires it. | Using masonry paint to conceal active damp or unsound render. |
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