A good foundation will make your special paint effect or paper much easier to do. Indeed, a poor foundation can destroy the whole effect -watching paper fall off inadequately prepared walls or patches of glaze go dull where the base was not covered, can be soul-destroying.
Different surfaces require different preparatory treatments, which depend to some extent on what you intend to do later. Some paint effects work on emulsion, while others need oil-bound bases. Wallpaper requires a different preparation from paint, and so does lining paper – this is often hung as a backing to wallpaper or to give a sound surface for the paint effect. Below are some of the types of surface you may encounter and details of how to prepare them for painting, papering and special paint effects.
Walls and Ceilings:
Old or painted walls should be washed down with sugar soap solution, then rinsed oil and allowed to dry. Rout out any cracks with a screwdriver or blunt chisel and dampen the edges of cracks and pits before filling them with proprietary filler. Over-fill slightly so that you can sand back after the filler has dried. Remake chipped external corners and repair internal corners using your finger or a flexible fillet knife.
When sanding the dried walls, make sure they are as flat as possible – take care to flatten patches of filler. Use sandpaper on a block for this stage. Feel with your hand to check that the surface is smooth, and brush oil or vacuum up the sanding dust afterward. Hiring a power sander is a great time-saver for large expanses of wall.
New walls, or new plaster, need four to six weeks, according to the temperature and conditions, to dry out fully. They may still lend to crack a little, so, although they can be painted in the meantime, they should not be papered. Any new plaster needs to be sealed. Because of its propensity for absorption, you must apply a ‘mist coat’ of paint before emulsioning a new wall. This is a very thin coat of emulsion paint, diluted 50:50 with water. Cover the wall completely in this mist coat and let it dry. If the mist coat is not applied, the water in the emulsion paint will be absorbed rapidly into the plaster wall and the paint will soon start to peel off.
Papered walls, and the question of whether or not to strip them depends on what you intend to do afterward. You can paint directly on to many matt-surfaced wallpapers. In this case, check that the surface is even, that the paper is stuck down anywhere it ma)’ be lilting, such as at the seams, and that any tears or missing pieces are repaired.
If the paper is vinyl, or if you intend to paper or paint directly on to the wall surface, then the wall needs to be stripped. It is claimed that some vinyl wall coverings can be stripped off in two layers so that you can remove the top layer and leave the backing paper underneath as a lining if you wish. In practice, this is rarely advisable, as you are wholly dependent on how well the paper was hung and on the even adhesion of the original paste. What can happen is that the new paper will be fine when it first goes up and sticks to the backing paper. But some time later, wherever the underneath paper comes unstuck the extra weight will bring old and new paper off together. You are usually better off taking the time to strip it.
Soak the wall with hot water containing a liberal amount of washing-up liquid and strip the wallpaper off with a rigid metal scraper. Alternatively, hire a steamer for the purpose. Remove all the paper and then treat the wall as for painted surfaces, sanding it smooth and wiping away the sanding dust.
Plasterboard walls must be dry stripped, as plasterboard will not tolerate extensive wetting. Otherwise treat as above, sanding the surface smooth when you have finished.
Woodwork: This will be either new or painted. You do not generally have to strip painted wood if you intend to paint it again, but it must be thoroughly cleaned to remove any grease and then sanded to key the surface. If there is a heavy build-up of old, chipped paint which it is necessary to strip, use paint stripper and a metal scraper or else a hot air gun. In either case, follow the manufacturers instructions carefully and take all necessary precautions.
New wood must be knotted and primed before sanding. Paint the knots with knotting solution and paint the woodwork with primer first. Fill cracks in new or old woodwork with fine surface filler. Allow to dry, then sand away any nibs until the surface is completely smooth. Where knots show through woodwork that has already been painted, treat them with knotting compound before repainting – just as if it was new wood. In this case there would be no need to prime the wood. You can repaint it after sanding.