Most flaws in paint surfaces can be avoided if you are scrupulous in your preparation and always use the correct materials. Even with the utmost care, however, some problems may occur, but these can usually be salvaged and sometimes do not entail too much extra work.
This is caused by moisture or air trapped beneath a coat of oil-based paint. The answer is to strip off the paint, carefully fill any holes and then repaint. With wood, it may be necessary to prime, undercoat and then repaint.
When the new surface reacts badly to what is underneath it, flaking occurs. Emulsion paint, for example, can flake when painted over a high-gloss finish or distemper. Unfortunately if this occurs there is no alternative but to strip the flaking surface, get back to the base, prepare it again properly and paint the area again.
If you apply a second coat of oil-based paint, such as eggshell, before the first coat has dried thoroughly, the surface may wrinkle. Strip the paint and reapply it.
Runs and drips
Possibly the most common problem, runs and drips are caused by loading too much paint onto the brush. Let the paint dry, rub the proud blobs gently with fine-grade sandpaper, remove the dust created by the sandpaper and touch up with fresh paint.
This occurs when a layer of new paint reacts badly with a painted surface underneath, or if layers of paint have different drying times. The only option is to repaint, removing all the layers of paint and preparing the surface again from scratch.
Grit, dust or insects in the paint
If this occurs, wait until the paint dries, then sand the area gently with fine sandpaper and wipe off the dust. If you sand lightly enough, you may not need to touch up the paint.
Stains in paintwork
Stains occur when insufficient preparation is done before the emulsion is applied. Mineral salts, moulds and other residues and impurities can react badly with the water in emulsion and will seep through the surface. Get back to the original surface and coat it with a proprietary primer-sealer and when that has dried, repaint.
This is most likely to show when you are applying a light colour over a dark base.
Streaky flashes of the base colour will appear under the top coat. Apply further coats of paint, until you have a solid top colour.
Cleaning your equipment after you have finished painting will significantly prolong its life. Brushes, rollers and pads that have been used with emulsion or other water-based paints should be rinsed with cold water to remove excess paint, paying particular attention to the base of the bristles, and then washed in a weak solution of warm water and detergent to remove the residue.
Equipment used for oil-based paint or varnish should be cleaned with turpentine, white spirit or a proprietary cleaner, ensuring that it is worked well into the bristles or pile. When all the paint has been removed, all equipment should be rinsed thoroughly in warm water and shaken vigorously to remove the excess.
To keep their shape, brushes can be wrapped in clean paper towels fixed with masking tape. Hang up brushes and rollers, and place pads face-up to maintain the pile, and your equipment should last you for years.