Paint Problems
If the surface to be painted has been well prepared (see "How do I prepare the surface prior to painting?" ) and paint is applied as directed, it is likely that repainting will not be necessary for several years. Coatings subjected to extreme weather conditions may need more frequent attention.
However, if a surface has not been sufficiently prepared, some problems may occur:
Cracking occurs when the top coat of paint is unable to expand to the same degree as the previous coating. This occurs commonly when an undercoat has not been given sufficient time to dry, or indeed if a paint is encouraged to dry too quickly, for example by increasing the temperature in a room or if decorating exterior surfaces in excessive heat. Cracking will also occur if wallpaper adhesive is allowed to dry on new paintwork.
Mould can appear as multi-coloured spots or patches, and growth of mould is encouraged by dampness and poor ventilation. It may also appear where paint has been applied to wallcoverings laid using unprotected paste – all wallpaper adhesives now contain fungicides to minimise the risk of mould growth.
It is certainly not worth simply painting over any mould patches as the patches will reappear. The cause of the dampness needs to be found and treated, and then sterilised either using a fungicidal solution or a 3:1 mixture of water and household bleach. It is then important to leave the area for at least a week to check for any reappearance of mould before repainting. It is then advisable to coat with a paint containing a fungicide. Remember to avoid splashes of fungicide on the skin and accidental consumption by children and animals.
Specialist products are available to treat the effects of damp. These act as a barrier to limit the risk of new decoration being spoilt.
Peeling or flaking can occur when the underlying surface has not been sufficiently prepared (see "How do I prepare the surface prior to painting?"), if dust or dirt particles remain on the surface or if the surface is still damp or unstable, or if rust is forming under the paint surface. As with cissing (see below), peeling may also occur if paint has been applied on a very shiny surface. Shiny surfaces may be lightly sanded prior to application of paint.
Chalking is the appearance of a powdery deposit on the surface of dry paint. It occurs most commonly when paints manufactured for use on interior surfaces are used on exterior surfaces, when paints have been over-thinned causing a deficiency in binder, or when paints have been applied before a surface has been sufficiently sealed, e.g. on new plaster. Remember to always choose the correct paint for the surface being painted and to always follow the instructions on the tin.
Blistering is when a paint or varnish forms bubbles on the surface. This could be due to too much paint being applied in one go, moisture trapped in the underlying plaster, using non-heat-resistant paints near sources of extreme heat. Blistering can also occur if an underlying wallpaper has not been hung using sufficient adhesive as the addition of a coat of paint could cause it to ‘bubble’ (remember though that if painting over lining paper, blistering that appears within a few minutes of painting usually flattens out during the drying process). To rectify, the blistered paint must be removed, and the surface made clean and dry prior to repainting with an appropriate paint, either one that is permeable (where damp) or heat-resistant if required.
Cissing is when the paint fails to form a continuous film on the surface, peeling back when it is applied leaving small round bare patches. This is due to painting either a greasy or oily surface, or painting very smooth and shiny surfaces. It can occur when emulsion paint is applied over oil-based paints, regardless of gloss.
The surface should be thoroughly washed with sugar soap and rinsed, and shiny surfaces may be sanded lightly prior to applying paint.
