Ask any professional decorator what separates a great finish from a mediocre one, and they'll tell you the same thing: preparation. The paint is almost the easy part. What comes before it — the filling, sanding, priming, and cleaning — is where the result is made or broken.

This is true whether you're repainting a single bedroom or redecorating an entire house. The fundamentals don't change.

Start with a thorough inspection

Before you open a tin, walk around the room slowly and look at every surface. You're looking for:

  • Hairline cracks — common around door frames, windows, and ceiling joins
  • Larger structural cracks — these may indicate movement and should be monitored before being filled
  • Flaking or bubbling paint — a sign of moisture or adhesion failure beneath
  • Stains — nicotine, damp, or watermarks need treating before they bleed through
  • Holes and dents — from picture hooks, screws, or general wear

Make a note of everything. It's easy to miss a crack when you're focused on a different wall, and you'll save time by addressing everything in a single preparation pass.

Filling: don't rush it

Most DIY painters apply filler, let it dry for an hour, and then sand. That's often not long enough. Filler shrinks as it dries, which means shallow fills can appear to vanish — only to reappear as shadows once the paint goes on.

For deeper holes (anything over 3mm), apply filler in layers, allowing each to dry fully before adding the next. For hairline cracks, use a flexible decorator's caulk rather than rigid filler — it moves with the building and won't crack again.

The golden rule: overfill slightly, then sand back to flush. Never try to fill exactly to the surface level — you'll always end up with a slight depression.

Sanding: the step people skip

Once your filler is dry, sand all repaired areas back to flush with the surrounding wall. Then — and this is what most people skip — lightly sand the entire surface you're about to paint.

This does two things. First, it removes any sheen from the existing paint, giving the new coat something to grip. Second, it smooths out any marks or texture inconsistencies that would otherwise show through.

For walls, 120-grit sandpaper is usually right. For woodwork, start at 80-grit if you're working back painted surfaces, then finish with 180-grit before priming.

Cleaning: the final step before paint

Dust, grease, and nicotine residue will all prevent paint from adhering correctly. After sanding, wipe all surfaces down with a damp cloth and allow them to dry completely. For kitchens or rooms where cooking grease may have settled on the walls, use sugar soap — it cuts through residue effectively and rinses off clean.

Priming: when is it necessary?

If you're painting new plaster, priming is essential — not optional. New plaster is highly porous and will suck moisture from emulsion paint unevenly, leading to a patchy finish that no amount of top coats will fix. Use a mist coat (emulsion thinned roughly 10:1 with water) to seal the surface first.

For previously painted walls in good condition, you may be able to skip priming if you're using a good quality paint and staying in a similar colour. But if you're going dramatically lighter or darker, or painting over a strong colour, a tinted primer will save you coats and money.

Preparation takes time — often as long as the painting itself. But it's the difference between a finish that looks good for two years and one that looks good for ten. If you'd like a professional finish without the work, get in touch for a free quote.