Painting a house wall is one of the oldest forms of decoration and still very popular. The best materials for amateur use are almost certainly the modern emulsion paints. These are water-solvent paints, but dry very hard. In fact a good emulsion paint may be scrubbed clean if it gets dirty.
The washable distempers, which are somewhat cheaper and which were used more in the past, are not quite so resistant although they do have much greater wearing capacity than older kinds. Emulsion paints rarely flake off, whereas distempers frequently do so after a year or two.
Oil paints are still sometimes used for walls, especially in kitchens and bathrooms. Sometimes difficulties arise in using this sort of paint on plaster. Many plasters give off salts of different kinds and may have a chemical content which affects the paint. This is much more likely to happen with oil bound paints than with emulsion paints for various technical reasons. It is worthwhile before considering oil painting a wall, to consult a skilled paint dealer and to follow his advice very carefully.
Usually, several coats will be applied, starting with a primer over the bare plaster followed by undercoats and finally by a gloss coat or a varnish.
There are few practical difficulties in applying paints. Oil paint, of course, takes more effort than the lighter-bodied water-bound paints.
But no matter which material you choose one factor is paramount. You must prepare the surface properly beforehand. Otherwise, it will be quite impossible to get a good finish. No paint will stick properly to large greasy patches, as may be found in kitchens, and these must be completely removed. Similarly, it is useless to paint a loose flaking surface because the paint will stick to this and not to the solid base. Before long it will flake away.
Many plasters are absorbent and unless they are properly primed, using materials to suit the paint being put on, they will absorb the water or oils from the paints. This creates drying problems and may weaken the paint film too. Emulsion paints present fewer difficulties of this sort.
Our best advice when deciding on paint work for a wall is to select a first class grade of emulsion paint and to apply it over a well-prepared surface in two, or even three coats. Remember however that emulsion paint dries very hard indeed and is difficult to remove. Any spots that fall from your brush or roller must be cleaned up with a wet cloth, immediately.
Skilled workers frequently prefer to use a brush for application, but a roller is probably easiest for the amateur to use. Be sure to get one of good quality, for the cheaper sorts clog and become much less efficient.
If you do choose brushes, you will find a wide range of quality and price. It is easier to make a good finish, especially with oil paint, with a brush which has first class long bristles but for the average job of emulsion-painting a room even a cheap brush will do quite a reasonable job. It may tend at first to shed a few bristles but most of the really loose ones will come free within a few minutes. They can be picked off the surface as you go along.
One dodge is to roll a new brush rapidly between your hands so as to fling out any loose bristles by centrifugal force. Similarly, you can pass the bristles through your pinched fingers to remove any that show signs of being loose.
If, however, you intend to paint regularly then certainly we recommend buying the very best possible brushes. Good quality brushes withstand years of wear if they are properly cared for and will prove a good investment. They are less likely to clog at the base of the bristles which will be longer, more flexible and generally of better quality.
Even if you mainly use rollers you will still need a small brush with which to paint the finer corners of the room and the extreme edges around doors and window frames.
As with all wall treatment, a good surface is essential for painting. Where the wall has previously been painted this must be cleaned down thoroughly. On a sound surface you can probably get a good key for the new paint simply by rubbing the surface all over with a fairly coarse piece of sandpaper. Surfaces that are too flaked and damaged to form a good base, must be removed. You can do this either with a blow lamp or by using chemical solvents.
Modern blow lamps use bottled gas and are very effective indeed but there is a certain amount of skill involved in using them without damaging the woodwork (or yourself).
On the whole we recommend that you stick to chemical solvents at first. These are simply brushed over the old paintwork. This will then soften and can be scraped away. You may need several applications to get it all off. For this job you will need a number of metal scrapers of different shapes so that you can get into the cracks and joints of the wood-work. Most of the work is done with a broad 3 in. scraper with a straight tip. Incidentally, many people start out scraping off paint using the tool upwards. This is inevitable of course near the top part of the wall but as often as possible it pays to work downwards. That is, to scrape from top to bottom, pushing the dissolved paint downwards with the tip of the tool. In this way the paint falls clear of ones hands and of the already-scraped surface.
Most newcomers lay on paint too thickly. This causes streaks and runs. Two thin coats are always better than one thick one and, surprisingly, do not usually take much longer to apply. Thin coats dry quickly, but a heavy one is slow.
Ordinary oil paints are finished by ‘stroking’ the surface with the brush tip, but the excellent, hard-wearing polyurethanes are simply laid on and will find their own level. The makers usually instruct about this.
Finally, do not forget to buy a supply of thinners suited to the paint. Keep part of this clean, for thinning the paint, and save the other part for brush cleaning and so on.