DEALING WITH PAINT PROBLEMS
The main causes of paint breaking down in the most residential and commercial painting jobs are incompatible paints being applied on top of one another, poor preparation of the surface, damp or trapped moisture, grease, rot or rust.
FLAKING
The paint has not been keyed to the surface, which may be too smooth (as with old gloss paint) or may be chalky (as with untreated kalsomine). Alternatively, rotting timber may be pushing the paint off or rust may have formed underneath
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- Strip small areas by rubbing gently with fine abrasive paper, fill with a fine surface filler, apply a primer and repaint.
- larger areas must be completely stripped and prepared again from scratch.
BLISTERING
Prick a blister – if water emerges, damp is trapped under the paint or is finding its way in from behind.
- Strip the blistered paint with a hol-air gun and leave until it has dried.
- Prime the surface and then repaint the whole of the repaired area.
CRAZING
When a paint surface breaks up like mini crazy paving, incompatible paints have been used. The top layer of paint
breaks up because it expands at a different rate from the one underneath.
- Usually, you must strip the paint with chemicals or a hot-air gun and start again.
- Rub down very small areas – no more than a few centimetres square – with a flexible sanding pad or with wet-and-dry paper dampened with water.
- When the surface is smooth, fill the stripped area with a fine surface filler, prime and repaint
VISIBLE UNDER-COLOUR
Some strong colours are difficult to paint over effectively.
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A tinted undercoat can help, depending on what colour (or white) is to be the new topcoat. Apply two or three topcoats.RUNSToo much paint applied in a thick coat results in runs that are hard to disguise
- If the paint is still wet, brush out runs; but not if the paint has started to dry. Instead, wait until it is completely dry and then rub down with very fine abrasive paper until the surface is smooth.
- Clean with a damp rag.
- Apply a new thin topcoat
- Prevent stains by treating them with a bleed sealer before you start painting.
- If the problem, occurs afterwards, brush a primer-sealer over stain and then repaint.
MOULD AND DISCOLOURATION
Spores settling on paintwork that is damp – possibly due to condensation forming on it-often lead to mould patches.
- Treat the affected area with a fungicide as directed by the FLAWS AND SPILLS manufacturer, wash the surface clean, let it dry and then repaint.
- Rub down with damp wet-and-dry abrasive paper.
- Brush off the dust and wipe with a clean, damp rag, then apply a new topcoat.
- Strip the paint with a chemical stripper or heat and redecorate, this time allowing each coat to dry before applying the next.
- When a gritty surface is dry, rub down with a damp wet-and-dry abrasive paper until it is smooth, wipe clean, then apply a new coat of paint.
- Open all the windows and doors or put a heater in the room.
- If these efforts do not solve the problem, the paint has been applied to a dirty – and quite probably greasy surface.
- Strip off the paint with chemical stripper or a heat gun and start again, taking great care to clean the surface thoroughly.
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