Preparation Decides the Finish

Ask any decorator what separates a professional-looking paint job from an amateur one and you will hear the same answer: preparation. Paint is only as good as the surface it sits on. A tin of premium gloss applied to a greasy, glossy, un-sanded surface will flake, peel and show every brush mark within a year. A modest mid-range paint applied over properly prepared timber will still look crisp after five.

In a typical UK home, woodwork takes a beating. Skirting boards collect scuff marks, door edges get knocked by shopping bags, window sills sit in condensation, and stair spindles are handled daily. That means the finish needs to be tough as well as neat. Fortunately, the two go together. Time spent on filling, sanding and cleaning is what gives you a smooth, durable film that resists chipping and wipes clean easily.

Choose the Right Coating for the Job

Before you open a tin, decide what you actually want the woodwork to look and feel like.

• Gloss is the traditional choice for skirting, doors and frames. It is hard-wearing, wipeable and reflects light, but it shows up every imperfection in the surface beneath, so preparation must be thorough.
• Satinwood and eggshell give a softer, lower-sheen finish that is more forgiving of small flaws and increasingly popular in period properties and modern interiors alike.
• Water-based paints dry quickly, smell far less and stay whiter for longer, though they need a little more care to apply smoothly.
• Solvent-based paints flow out beautifully, level brush marks well and feel harder when cured, but they yellow over time, particularly in rooms without much natural light.

Whatever you choose, buy a dedicated primer or undercoat to go with it rather than relying on the topcoat to do two jobs. If you are painting bare pine, add a knotting solution over any knots, otherwise resin will bleed through and leave brown stains within weeks.

Sanding, Filling and Cleaning: The Core Steps

Work through the prep in a sensible order. This sequence takes perhaps an hour for a single door and frame, and it is the hour that matters most.

• Remove hardware where you can. Handles, letter plates, hinges and latch plates come off far more easily than they clean up afterwards. Mask hinges if removal is impractical.
• Wash the surface with a sugar soap solution to cut through years of grease, fingerprints and furniture polish. Rinse and let it dry completely.
• Scrape and fill. Rake out any flaking paint back to a firm edge, then fill dents, splits and old screw holes with a two-part wood filler or a fine surface filler. Slightly overfill and sand flush.
• Sand bare timber with 80 to 100 grit to open the grain, then move to 120 grit. On previously painted wood, use 120 to 180 grit to dull the sheen and give the new paint a key. Feather the edges of chipped areas so they do not show as ridges.
• Deal with gaps. Where skirting meets wall, or architrave meets plaster, run a bead of decorator's caulk and smooth it with a damp finger. Paint over it once cured.
• Remove the dust. Brush down, hoover the area thoroughly, then wipe with a tack cloth or a lightly dampened cloth. Dust is the single biggest cause of gritty, bumpy finishes.

Priming and Undercoating

Bare wood is thirsty and uneven. A primer seals the grain, stops the topcoat soaking in unevenly and gives the paint something to grip. On previously painted surfaces in sound condition, you can often skip straight to a spot primer over filler and bare patches, provided the colour underneath is similar.

Undercoat does a different job: it builds a flat, uniform base and helps the topcoat cover in fewer passes. Tint your undercoat towards the final colour if you can — a mid-grey undercoat beneath white gloss will cover in two coats where a white undercoat might need three. Sand lightly with 180 to 240 grit once the undercoat is dry, and dust off again before continuing. If you switch between water-based and solvent-based products, check the tin for compatibility and always allow full drying time between coats.

Brushing Technique and Thin Coats

Two or three thin coats will always beat one thick one. Thick paint sags, runs, dries slowly, traps solvent and stays soft for weeks.

Load your brush to about a third of the bristle length, then tap off the excess rather than wiping it on the rim. Work in manageable sections of around a metre, brushing the paint out in one direction, then lay off lightly along the grain with the tips of the bristles to smooth the marks. Do not overwork the paint — the more you brush it once it begins to set, the more visible your strokes become.

Use a quality brush suited to your paint: synthetic filaments for water-based products, natural bristle for solvent-based. A cheap brush sheds hairs, splays and leaves ridges, and no paint is good enough to compensate. Keep a small brush for mouldings and a wider one for flat panels, and wrap brushes in cling film between coats rather than cleaning them every time.

Drying Conditions and Between-Coat Sanding

Aim for a room temperature of roughly 15 to 25°C with decent ventilation and low humidity. Cold, damp conditions slow curing dramatically and leave solvent-based paint tacky for days, which is why a February window frame is a frustrating job.

Between coats, denib the surface lightly with 240 grit or a fine sanding pad, just enough to remove dust specks and brush ridges. Wipe away the dust, then apply the next coat. Leave the final coat to harden fully — several days for solvent-based paint — before hanging curtains, refitting hardware or wiping the surface down. Once cured, clean with a soft damp cloth and mild soap rather than abrasive cleaners, and touch in any knocks promptly to keep the finish intact for years.