Preparing walls and woodwork for painting

Clearing and protecting the room

Furniture is moved out, or to the middle of the room and covered. Floors are covered with dust sheets: cotton sheets stay put and absorb drips, while thin polythene is slippery underfoot and lets wet paint travel on the soles of shoes. Curtains, pictures, hooks and shelves come down.

Sockets and light switches can be loosened a few millimetres from the wall so that paint runs behind the edge of the faceplate, but only with the electricity switched off at the consumer unit. Otherwise they are masked.

Checks before sanding

• Lead. Wood and metal painted before the 1960s may have lead paint among the lower layers.
• Asbestos. Textured coatings on ceilings and walls, of the kind often known by the brand name Artex, may contain asbestos if applied before 2000.

Both are dealt with under lead paint, asbestos and paint disposal. The short version is that sound surfaces are left alone and painted over, and nothing of either kind is sanded dry.

Washing

Walls and woodwork are washed to remove grease, dust and the film left by cooking and smoke, to which paint will not stick. Sugar soap, a mild alkaline cleaner sold for the purpose, is the usual choice. It is rinsed off with clean water and the surface left to dry.

Black mould is treated with a fungicidal wash, not painted over. It returns unless the cause — condensation, a leak, poor ventilation — is dealt with.

Filling and sanding

• Loose and flaking paint is scraped back to a firm edge.
• Cracks and holes in plaster are raked out, filled slightly proud of the surface with filler, left to harden and sanded flush. Deep holes are filled in layers.
• Gaps between skirting boards or door frames and the wall are closed with decorator's caulk, a flexible filler applied from a cartridge and smoothed with a wet finger. It cannot be sanded, and it moves with the joint where rigid filler would crack.
• Glossy woodwork is rubbed down with fine abrasive paper to dull the shine, which gives the new coat a key. The old paint need not be removed if it is sound.
• Walls are sanded lightly where filled, and all dust is removed with a vacuum cleaner and a damp cloth before any paint is opened.

Sanding produces fine dust. A disposable mask rated FFP2 or FFP3 filters it; a simple paper dust mask does not.

Wallpaper

Sound, well-stuck paper can be painted over, though the seams will show. Paper that is lifting is stripped: scored, soaked with warm water or a steam stripper, and scraped off, after which the wall is washed to remove the paste. Where plaster is cracked or uneven, lining paper gives a smooth surface to paint.

New and bare surfaces

New plaster is left until it has dried to an even pale colour, which takes weeks, not days, and is then sealed with a thinned mist coat. Bare wood is primed, with knotting solution on the knots. The products are described under types of paint.

Masking

Masking tape protects the edge of anything not being painted: glass, floors, fittings, the line between wall and ceiling. Decorator's tapes are graded by how firmly they stick and by how many days they can be left in place, and both figures are printed on the roll. Low-tack tape is used on fresh or delicate surfaces, including paint less than a few weeks old.

• The tape is pressed down firmly along the painting edge, so that paint cannot creep beneath it.
• It is removed while the last coat is still slightly soft, pulled back on itself at a low angle.
• Tape left on beyond its stated time, or in strong sun, tears and leaves adhesive behind.

A steady hand with a good brush makes much masking unnecessary, and professional decorators use far less tape than amateurs.