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Surface preparation: the step people skip, and what it costs

Most paint failures are preparation failures. What sanding, filling, putty and primer actually do, how to tell if they were done, and where to spend the time.

4 min read · Updated 19 August 2026

If a paint job fails early, the fault is nearly always in what happened before the colour went on. Paint is a thin film that can only grip what it is put on. Put it on dust, chalk, algae, powdery distemper or hollow plaster, and it grips something that is already letting go — however good the tin was.

Preparation is also the invisible part, which is why it is the part that gets cut when a quote is squeezed. A finished wall looks identical on handover day whether it was washed and primed or not. The difference shows up in the second year.

What each step is actually for

Cleaning. Removes dust, cobwebs, grease near the kitchen, salt deposits on coastal-facing exteriors, and the chalky powder an old exterior coat leaves behind. This is not cosmetic — anything left on the wall becomes the layer the new paint sticks to.

Scraping and removing loose material. Flaking paint, blistered film and old distemper all have to come off. Tap suspect plaster; a hollow, drummy sound means it has lost its bond to the wall and must be cut out and re-plastered.

Treating algae and fungus. Common on shaded and north-facing walls after the monsoon. Painting over live growth means it comes back through the new film.

Crack filling. Hairline crazing takes a filler or putty. Anything wider is opened out first so the filler has a body to hold onto, then filled in layers. Filling a narrow crack on the surface only means it reopens at the first hot spell.

Sanding. Knocks back ridges, old brush marks and filled areas so the surface is flat and slightly keyed for the next coat.

Putty. Levels the wall and gives a smooth base. Applied in coats, sanded between them. Needed under sheen finishes and on new or patchy plaster; optional on sound walls with a matt finish.

Primer. Seals the surface so the topcoat is absorbed evenly, and provides the bond. Without it you get patchy sheen, uneven colour depth and a topcoat that lifts where absorption was highest.

The Nellore-specific parts

  • Salt on coastal exteriors. Homes towards Muthukur, Krishnapatnam and the eastern edge of the city collect salt deposits that must be washed off, not brushed. They sit invisibly on the surface and stop the primer bonding.
  • Post-monsoon moisture. After October to December rain, walls hold water for weeks. Preparation includes waiting. Tape a foot-square piece of plastic sheet tightly to the wall overnight; condensation under it in the morning means the wall is not ready.
  • Dust on main roads. A wall facing a busy road needs a proper wash, and windows and openings need to be kept shut while the coat is wet, or the dust becomes part of the finish.
  • Hard-water marks. Mineral deposits from borewell water splash lines have to be cleaned off, or they show through as pale patches.

How to tell whether it was done

You can check without any expertise:

  • Was the surface washed and left to dry, or did painting start on day one?
  • Are the drop sheets and masking in place before any coat goes on?
  • Run a hand over a filled patch after sanding — it should feel level with the wall, not proud of it.
  • Ask which primer is being used and see the tin. "Primer" that turns out to be thinned topcoat is a common shortcut.
  • Look at the wall in raking light from a window. Ridges, roller edges and unfilled dents are visible before the topcoat, not after.

What you can do yourself, and what to leave

Dusting down reachable interior walls, taking down curtains and pictures, and pointing out every stain, crack and past damp patch before quoting are all genuinely useful and save time. Leave the scraping, plaster repair, putty and anything at height to the crew — plaster removal creates a lot of dust and mess, and ladder work above ground level is not worth the risk.

Call someone in before painting if plaster sounds hollow anywhere, if a wall has a damp history, if the existing coat is distemper, or if previous paint peeled in sheets. Each of those changes the preparation needed, and therefore the quote. Our interior pricing — ₹3,499 for a single room, ₹8,999 for a 1BHK in primer plus two coats, ₹13,999 for a full 2BHK repaint — assumes walls in normal condition, and materials are charged at MRP and shown before use. Walls that need re-plastering or damp repair are extra work, and you should hear that at the survey rather than after the job begins.

Questions people ask

How much of a paint job should preparation take?
On a repaint of walls in decent condition, roughly a third to a half of the total time on site. On walls with old distemper, damp history or patched plaster it can be more than the painting itself. A crew that arrives and starts rolling colour within the first hour is not preparing anything.
Is wall putty always needed?
No. Putty levels a surface and gives a smooth base for premium finishes. On sound walls that already have a good even coat and where you want a matt finish, spot filling and a primer are often enough. Full puttying is worth it on new plaster, patchy walls, or under a sheen finish that shows every defect.
Can primer be skipped if the old paint is still good?
Sometimes, if the existing coat is sound emulsion, clean, and the new shade is similar. It cannot be skipped over new plaster, over any repaired or filled area, over distemper, or when going from a dark shade to a light one. Primer is what the topcoat bonds to and what stops patchy absorption.

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