How are cracks in plaster typically repaired?

How are cracks in plaster typically repaired?

• A. Clean crack, apply bonding agent, fill with compatible plaster mix, and feather edges
• B. Paint over cracks
• C. Ignore cracks
• D. Replace entire section

Answer: (A)

When plaster cracks, the repair aims to restore adhesion and texture with a patch that matches the surrounding material, not just cover up the crack. Start by cleaning the crack to remove loose plaster and dust so the patch can bond properly. If any loose edges are present, lightly undercut or rake the crack to give the patch a better key. Next, apply a bonding agent to improve adhesion between the old plaster and the new material, especially if the surface is very smooth or dusty. Then fill the crack with a patching mix that is compatible with the existing plaster—use the same type (or a close match) of plaster as the original base coat (for example, lime-based for lime plaster, gypsum-based for gypsum plaster). This compatibility helps prevent future cracking from differential shrinkage or moisture. After filling, feather the edges so the repair gradually blends into the surrounding surface rather than forming a noticeable ridge. Once it cures, sand smooth and repaint to restore a uniform finish. For small cracks this approach is usually sufficient; painting over, ignoring, or replacing an entire section is not appropriate for typical cracks, which is why the method described is the proper repair.

When plaster cracks, the repair aims to restore adhesion and texture with a patch that matches the surrounding material, not just cover up the crack. Start by cleaning the crack to remove loose plaster and dust so the patch can bond properly. If any loose edges are present, lightly undercut or rake the crack to give the patch a better key. Next, apply a bonding agent to improve adhesion between the old plaster and the new material, especially if the surface is very smooth or dusty. Then fill the crack with a patching mix that is compatible with the existing plaster—use the same type (or a close match) of plaster as the original base coat (for example, lime-based for lime plaster, gypsum-based for gypsum plaster). This compatibility helps prevent future cracking from differential shrinkage or moisture. After filling, feather the edges so the repair gradually blends into the surrounding surface rather than forming a noticeable ridge. Once it cures, sand smooth and repaint to restore a uniform finish. For small cracks this approach is usually sufficient; painting over, ignoring, or replacing an entire section is not appropriate for typical cracks, which is why the method described is the proper repair.