01Common causes
Plaster shrinkage, heat expansion and humidity.
Hairline crack paint: how to fix and paint over cracks
Why hairline cracks appear and how to repair them so they don't come back.
Hairline crack paint and crack fillers help hide the thin cracks that appear on many Indian walls. These cracks are usually caused by plaster shrinkage, temperature changes or moisture, and they'll return through ordinary paint unless repaired properly.
Here are 10 things to know about fixing and painting over hairline cracks.
Wide structural crack compared to a hairline crack
02Structural vs hairline
Wide or growing cracks need an engineer.
Crack opened into a V-groove
03Open the crack
Widen slightly into a V to hold filler.
Applying acrylic crack filler
04Crack filler
Flexible acrylic fillers stay elastic.
Fibre mesh tape over a crack
05Fibre mesh tape
For recurring cracks, mesh reinforces the repair.
Sanding putty over a repaired crack
06Putty and sanding
Smooth the surface before primer.
Primer on a repaired wall
07Primer
Seals the repair.
Elastomeric paint on an exterior wall
08Elastomeric paint
Flexible paints bridge fine cracks.
Exterior crack being waterproofed
09Exterior cracks
Waterproof to stop rain entering.
Damp patch around a wall crack
10Fix damp first
Cracks with damp patches need waterproofing.
Repainting and repairing walls as part of a home update? Talk to our interior designers in Kolkata.
Steps to fix hairline cracks
- Inspect: is it hairline or structural?
- Clean and widen the crack slightly.
- Fill with flexible crack filler.
- Reinforce with mesh if recurring.
- Putty, sand and prime.
- Paint with a good emulsion or elastomeric paint.
Materials and rough cost factors
- Crack filler and mesh.
- Primer and paint type.
- Area and number of cracks.
FAQs
Frequently asked questions
Can paint hide hairline cracks?
Elastomeric paints can bridge very fine cracks, but cracks should be filled first.
Why do hairline cracks come back?
Ordinary fillers are rigid; walls move with heat and humidity. Use flexible fillers and mesh.
Are hairline cracks dangerous?
Usually not. Wide, diagonal or growing cracks need an engineer.
Which paint is best for cracks?
Elastomeric or crack-bridging paints.
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