Before you start painting, it is advisable to do all the required prepartion. The preparation that is required varies according to the surface to be painted but you must be aware that preparation is the key to a successful outcome of any decorating task and it may well take longer than the painting itself.
If you are going to paint on top of new plaster, this should always be allowed to dry thoroughly before it is decorated, however, there are specific emulsion paints for new plaster which you may want to check out. As the plaster dries it will change colour from dark to pale pink, and when it is dry any solids which appear on the plaster should be removed with a hessian or similar cloth.
Before applying the first coat of emulsion, a primer is required and usually the emulsion can be diluted (check the manufacturers instructions) to act as a primer.
If old plaster is clean, dry and sound, no special preparation is required. However if the surface shows evidence of old distemper residue or is powdery, it should be sealed with a stabilising solution which can be bought from most paint suppliers.
When renovating or removing paintwork, it is worthwhile reading the British Coatings Federation’s leaflet entitled “Old Lead Painted Surfaces – a guide on repainting and removal for DIY and professional painters and decorators” which is in our Resources section. Surfaces previously finished in matt, silk or satin emulsion paint and in sound condition merely require washing with a sugar soap solution which is thoroughly rinsed off. Gloss and traditional eggshell finishes, in addition, will require wet rubbing down to provide a key for the new paint.
With any of the above surfaces, any loose or flaking paint should be removed and sanded and noticeable cracks should be made good and the area primed before painting.
When painting over existing wallpaper, a successful finish will only be obtained if the paper is sound and adhering firmly to the wall, especially at the edges and joins. If painting over a coloured wallpaper, the colours (particularly reds) are liable to bleed and should be treated with a thin coating of stain sealer first. Metallic inks will eventually cause a discolouration of the paint film due to dirt retention on the colder metallic area.
To prepare wood, lightly abrade the surface using a dry sandpaper, rubbing in the direction of the grain. Dust off with a damp rag and allow to dry.
Remember to take adequate precautions when preparing surfaces, especially in relation to dust inhalation.