Interior painting prep, in the order that saves rework

Most disappointing paint jobs are prep failures, not paint failures. The work below is unglamorous and it is where the finish is actually decided.

The sequence that wastes the least effort is: clear and protect, clean, fill and repair, sand, caulk, spot-prime, then mask last. Doing them out of order mostly means doing some of them twice — sanding before filling, or masking before sanding, both guarantee a second pass.

1. Clear the room and protect what stays

Get furniture out if you can and into the middle under a sheet if you cannot. Take down switch and outlet plates rather than cutting around them; it takes two minutes and it is the difference between a crisp job and an obvious one. Drop cloths on the floor: canvas grips and absorbs, plastic is cheaper but slides underfoot and lets spills travel.

2. Clean the walls, properly

Paint sticks to the surface it touches, and if that surface is a film of kitchen grease or cigarette residue, that is what it sticks to. Wash walls with a degreasing cleaner and rinse; kitchens and any room where someone smoked need it most. Let everything dry fully — trapping moisture under a fresh film causes blistering weeks later.

Mildew is a special case. It has to be killed, not painted over, or it grows through the new coat. Treat it, rinse it, and let it dry before priming.

3. Fill and repair

Lightweight spackle handles nail holes and small dings and sands easily. Anything deeper than about a quarter inch wants joint compound built up in thin coats rather than one thick one, because thick fills shrink and crack as they cure. Cracks that keep reopening are usually structural movement, and taping the crack with mesh or paper before filling is what stops it coming back through next season.

4. Sand, and get the dust off

Sanding does two jobs: it levels your fills, and it dulls any glossy existing paint so the new coat has something to grip. A medium grit knocks down repairs, a fine grit finishes them. On glossy trim, scuff-sanding the whole surface matters more than it looks like it should.

Then remove the dust. Vacuum, then wipe with a damp cloth, and let it dry. Paint applied over sanding dust picks it up into the film and you will feel it for the life of the wall.

5. Caulk the gaps

A bead of paintable acrylic latex caulk where trim meets wall is the single cheapest upgrade to how a room reads when finished. It closes the shadow line that makes trim look separate from the wall. Use paintable caulk — pure silicone will not take paint and you cannot fix that afterwards. Smooth the bead with a wet finger and let it skin over before painting.

6. Prime what needs it

You do not always need to prime a whole room, but you do need to prime: bare drywall, bare wood, anything you filled, anything glossy, and any stain that would otherwise bleed through. Water stains, smoke and tannin-rich woods need a stain-blocking primer specifically, because ordinary primer lets them ghost back through the topcoat, sometimes weeks later.

Spot-priming repairs matters more than people expect. Filler is far more absorbent than the surrounding painted wall, so an unprimed patch drinks the topcoat and dries duller — the repair stays visible through two coats. That effect is called flashing, and priming the patch is the whole fix.

7. Mask last

Tape goes on after sanding and cleaning, not before, or you will be taping over dust and doing it again. Press the edge down firmly, and pull it while the paint is still slightly soft rather than after it has fully hardened, so the film parts cleanly instead of tearing.

Where to start

The paint and finishing department carries the primers, caulks, tapes, sandpaper and brushes this all runs on, and we are a Benjamin Moore dealer if you want their interior lines. Deciding which sheen to put over all this prep is its own question — the paint sheen guide covers it.

If you are matching an existing colour rather than picking a new one, bring a flat sample at least an inch square to the counter and we will scan it: see paint colour matching.