Expert Information And Advice On:     

(This topic is also categorized under Walls & Ceilings)

Painting Walls of All Types

When you are painting walls and ceilings, bear in mind the preparation of surfaces for paint is the most important part of the process. Without a smooth, clean and dry surface, no amount of care in applying the paint is going to give a professional finish.

New plaster

Make sure that new plaster is absolutely dry before applying paint to it; water trapped in the plaster weakens the adhesion of the paint and may cause blistering. Some plasters have an alkaline nature and when the plaster dries out, white fluffy alkaline crystals may be deposited on the surface. Remove these deposits with a dry brush before paining.

The plaster should, in any case, be dry-brushed before painting to remove surface dirt, and scraped to remove any plaster splashes. Make good any cracks or holes with a plaster-based or general purpose cellulose filler. After preparation, the plaster must be sealed. If you are using emulsion (latex paint), a coat of emulsion thinned with water is sufficient. With oil-based (alkyd) paint use alkali resisting primer.

Wallpapered surfaces

It is advisable to remove existing wallpaper before painting, as it is never possible to know how well the paper is adhering to the surface and the finished work can be spoiled later by unsightly blisters or lifting edges. Also, it is not normally possible to wash ceiling and wallpapers so nicotine and other deposits on the paper coating. This is especially true of emulsion paints, which are particularly good for dissolving nicotine. Stripping the wallpaper can be quite a difficult and time consuming job. If you have a large area, hiring a steam stripper will save a lot of time.

Old plaster walls

After stripping the old wallpaper, it is important to remove any trace of paste and size left on the surface as these can cause newly-applied paint to flake. Remove old paste by washing the wall with warm water and, when the surface is dry, sanding it with glass paper. Afterwards, fill the surface in the same way as you would for the new plaster.
If the surface is a mixture of bare plaster and painted areas, you can achieved a more uniform surface by first covering the wall with a heavy duty, 600 grade lining paper. Make sure that it is stuck well to the surface before you start painting.

Existing painted surface

Painted surface must be washed down to remove dirt and grease. In bedrooms and halls, a mixture of washing powder and warm water should be sufficient to remove it. But in kitchens, where the grease is thick, stronger cleaning agents such as a washing soda solution may be required. The walls must be rinsed afterwards, as residues may attack and soften the paint. Shiny gloss surfaces should be lightly abraded, then rinsed, to provide a good key for the new paint.

Emulsion Paint versus Oil Paint

Emulsion paints

Emulsion paints are produced with varying degrees of sheen. Matt emulsions have no sheen at all and are best suited to bumpy and old walls where any imperfections will not be so apparent. Emulsions with a small degree of sheen are often called silk finish (semi gloss). With these, any imperfection in the surface may be more apparent.

Emulsion paints dry by the evaporation of their water content, so when you are applying emulsion, keep the windows closed to stop it from drying too quickly Open the windows as soon as the work is completed to remove moisture from the atmosphere.

Oil Paints

These are generally more durable than emulsion paints and are well suited to kitchens and bathrooms where there is a lot of moisture.

Oil paint is available in gloss or eggshell (semi gloss finish). Although gloss required an undercoat if used on an unpainted surface, most brands of eggshell specify that two coats of the finish paint gives sufficient coverage.

Some brands of oil paint are supplied in jelly-like, thixotropic form. These are designed to produce thicker coatings and if applied correctly present fewer problems with drips and splashes. The jelly like characteristic breaks down as the paint is applied so it should not be over brushed or over rolled. When oil paint begins to dry the thinners base evaporates into the atmosphere and oxygen then combined with the oil in the coating to form a hard film. Because of this, you must complete each coat as quickly as possible and have adequate ventilation as you apply the paint. Lack of ventilation allows the solvent fumes to be inhaled: this combined with a lack of oxygen can result in headaches and nausea.