Help with paint How-to guides

Preparing a room for painting: the checklist

Prepare the day before, in eight steps: clear and protect, remove sockets and hardware, scrape what is loose, fill, sand, dust and wash, mask, then prime where the surface asks for it. Allow a day for a 15 m² room. It is the preparation, not the paint, that makes a flawless wall: a deep matt like Marble Matt Emulsion forgives small irregularities, never dust or grease.

Page updated September 2026 · by the Mylands France colour team

Empty room ready to paint: furniture grouped in the centre under a sheet, floor protected, grey-white walls filled and sanded, a stepladder and a tray by the window — The evening before: everything cleared, protected, filled, sanded — tomorrow, two coats

Why the day before

One day of preparation, one day of painting

The decorators' rule fits in one sentence: prepare one day, paint the next. The two coats of Marble Matt Emulsion of an average room fit into a day — touch-dry in 1 to 2 hours, recoatable after 3 to 4 — provided you start in the morning with walls ready and tools out. Preparing and painting on the same day means finishing the second coat by head-torch, and the next day's raking light will show you why that was a bad idea.

Preparation has a hidden advantage too: it makes you look at the walls up close. A running crack, a trace of damp, an old paper badly stuck are found at the filling stage, not with the roller. What you find the day before is fixed in an hour; what you discover under the first coat costs a day.

Dust sheets or old sheets for the furniture, paper or sheeting for the floor
Good masking tape, 25 to 38 mm
Filler (cracks) and skim filler (surfaces)
Abrasive paper, 120 for repairs, 180 for smoothing
Sponge, bucket, mild detergent or sugar soap
Screwdriver, filling knife, sanding block, vacuum cleaner

The method

The eight steps

01

Clear the room, or group everything in the centre

Take out rugs, curtains, pictures and small furniture. Push the large pieces to the centre, a metre from the walls, under a sheet. Cover the floor completely — sheeting, cardboard or paper — and tape the edges down: a drop of paint washes off, a drop walked on turns up in three rooms. Take down the light fittings you can, and switch the radiator off: you do not paint a warm wall.
02

Remove sockets, switches and hardware

Turn the power off at the board, unscrew the socket and switch plates (one turn of the screw and they come away), take off handles, hooks and pegs. Painting around a plate leaves a ring; painting under it takes a minute with a screwdriver. Keep the screws in a closed jar.
03

Scrape what is loose

Run the filling knife over any surface that blisters or flakes: new paint never holds better than the coat beneath it. On old wallpaper, check the seams; a gaping seam gets re-glued, a paper coming away in sheets comes off entirely. If the surface chalks — a finger run over it comes away white — it will need a stabilising primer before anything else.
04

Fill cracks, holes and joints

Cracks opened into a V with the knife, plug holes, the joint between skirting and wall: filler, slightly proud, then complete drying — respect the stated time, often longer than you think on a deep crack. Filler still damp under the paint gives a matt patch or a blister. For a badly damaged wall, a skim over the whole surface beats a hundred repairs.
05

Sand lightly, everywhere

The repairs with 120 grit to bring them flush, then the whole surface with 180, on a block, without pressing: the aim is to break the sheen of the old paint and even out the grain, not to bare the plaster. On an old satin or gloss paint this sanding is compulsory — it is what gives the key. Woodwork follows the same rule: see Wood finishes preparation.
06

Dust down, then wash

Vacuum walls, skirting and floor, then go over the whole surface with a damp sponge. In a kitchen or near a radiator, wash with mild detergent and rinse: grease and nicotine repel water-based paint. Let it dry for an hour. A clean wall is half the job.
07

Mask what will not be painted

Masking tape along the top of the skirting, around the windows, along the edges of already-painted woodwork; press the tape's edge down with a nail or a card so paint cannot creep under. On carpet, tuck the tape between the skirting and the pile with a filling knife. Remove the tape while the last coat is still slightly damp, pulling at an angle, for a crisp line.
08

Prime where the surface asks for it

New plaster, skim filler, a porous or strongly contrasting surface: a primer evens out absorption and saves a coat of finish. On a sound, already-painted surface in a similar shade, two coats of finish are enough. The table below says which. Then put the tools away, close the door and sleep: tomorrow, the wall.

Detail of a grey-white wall being prepared: a crack filled with filler, a sanding block, a filling knife and a damp cloth on a stepladder step — Steps 4 and 5: fill slightly proud, let it dry, bring flush with 120 grit

Reference

Which primer for which surface

Allow about half a litre of primer per litre of finish. Every Mylands primer is water-based and recoatable after 3 to 4 hours.

The surface	What it needs	Why
Already-painted wall, sound, similar shade	No primer	Two coats of Marble Matt Emulsion cover
New plaster, skim filler, plasterboard	Wall Primer	Seals the surface, evens absorption, avoids dull patches
Dark wall to be repainted light	Wall Primer, or Primer & Undercoat in the finish's tone	One coat of primer replaces a third coat of finish — see How to paint a dark wall white
Deep or highly saturated colour	Tinted Primer & Undercoat (dark grey, red, blue…)	The tinted base gives the colour its depth in two coats
Chalking surface, old distemper	Stabilising Primer, then Wall Primer	Binds the mineral dust the paint cannot hold on to
Woodwork, doors, metal	Multi-Surface Primer on bare wood and bare metal	The multi-surface finishes hold on the primer, not on raw wood
Old, dried damp stain	Treat the cause, then a stain-blocking primer	Without a blocker the stain bleeds through water-based paint

An active damp patch, mould or a weeping wall are not painted: repair first. The other defects and their remedies: Paint problems, causes and fixes.

To avoid

The five shortcuts that show

Painting around socket plates. A ring of the old colour at every switch, to save three minutes.
Filling and painting on the same day. Damp filler makes a matt patch under the coat and blisters in the first sun.
Not sanding an old satin. The new paint slides and flakes under a fingernail six months later.
Skipping the wash in a kitchen. Invisible grease makes water-based paint bead.
Removing the tape the next day. Dry paint bridges the tape and tears away with it: remove it damp.

The same room painted: flawless matt grey-white walls, warm white skirting, socket plates back on, raking light with not a flaw to see — The next evening: St Clement No.11 on the walls, Whitehall No.9 on the skirting, and nothing to redo

Frequently asked questions

Your questions, our answers

Do walls always need washing before painting?

In a kitchen, a bathroom, a room where people smoke or near a radiator, yes. In a clean bedroom, a damp sponge after vacuuming is enough. The test: wipe with a damp white cloth; if it comes away grey or yellow, wash.

Can I paint over wallpaper?

Over a smooth, well-stuck, sound paper, yes, after a wall primer: it blocks the paste and evens the surface. Over a vinyl, embossed or peeling paper, no: strip it. A paper seam will always show under matt paint in raking light.

How long does filler take to dry?

A thin repair, two to three hours; a deep crack or a plug hole, often overnight; a skim over the whole surface, 24 hours. The maker states a time; add half again in a cold or damp room.

Is the ceiling prepared the same way?

Yes, and first, since you paint from the top down: dusting, filling the cracks, light sanding. An old water stain on a ceiling needs a stain-blocking primer or it will bleed through. Which white to choose: which white for a ceiling.

When can the furniture go back?

The day after next for pieces that do not touch the walls, a week for those that lean on them. Paint is dry in a few hours and hard in two to four weeks: a sofa back against yesterday's wall leaves a shiny mark.