Plaster, Filler and Primer

Once everything that isn't holding has gone, the wall is built back up layer by layer: plasterRender (plaster)A layer of mortar (sand, cement or lime, and water) spread over brick or concrete to give a wall a straight, sound surface ready for paint or tiles. where it's missing, fillerFillerA fine paste or powder that fills holes, fine cracks and dents so a wall, ceiling or piece of wood is smooth before it is painted. for the small flaws, sandingSandingSmoothing a surface with sandpaper or a power sander to remove bumps, loose old paint or gloss, so the new paint or varnish grips well and comes out smooth., primerPrimerThe thin first coat that goes on before the main material. It binds dust, seals the pores and helps paint or waterproofing stick firmly. and, last of all, the paint.

New plaster where it has gone

Areas scraped back deeply are filled with new plaster until they are level with the rest of the wall. In one apartment, damp had ruined a whole strip of plaster in the corner beside the window, from the ceiling down. With new plaster and paint, the corner no longer stands out from the rest of the wall. In another apartment the section of ceiling that had fallen was plastered again.

New plaster has to dry well before it is painted. How long that takes depends on its thickness, the season and how well the room is ventilated.

Filler and sanding

Small dips, the edges of scraped areas and holes are filled. The white patches you see on walls before painting are exactly that. They are then sanded so they are flush with the rest of the wall and don't show under the paint.

Primer

Patches, new plaster and old paint don't take up paint the same way. Primer evens out the surface so the final paint spreads evenly. In an office, a first coat went onto the repaired areas and then across the whole wall under the window, down to the skirting.

Where water or sootSootThe black, greasy dust that smoke leaves on walls and ceilings after a fire, or from a fireplace or stove. Paint straight over it without cleaning and priming and it comes back through. stains remain, a stain-blocking primer is needed. Otherwise they come back through the new paint, however many coats go on.

The whole wall, not just the patch

A patch painted on its own shows, because the old paint has changed shade over the years and filler takes up paint differently from the rest of the wall. That's why the new paint goes over whole walls, corner to corner. In an entrance with peelingPeeling paintWhen paint loses its grip and lifts off in flakes or sheets. It is almost always a sign of a problem underneath, usually damp or poor preparation. patches next to the door and the stairs, the patches were repaired and then whole walls were painted, so there were no differences in shade.

Paint for damp-prone rooms

In kitchens, bathrooms and rooms with condensationCondensationMoisture in the air turning to water on cold surfaces such as windows, outside corners and ceilings. It is the most common cause of mould indoors., a washable paint helps. There are also paints with anti-mouldMouldFungi that grow on damp surfaces, leaving black or greenish spots and a musty smell. It is a symptom of damp, not a problem with the paint. additives. But no paint stops damp: if the cause remains, the damage will show again. In these rooms good ventilation matters more than the paint.