Common problems

Blistering and flaking

Cause

Flaking is likely to be caused by poorly adhering, powdery old coatings. Check for the presence of powdery coating by rubbing your hand over the surface - powder on your hand indicates a problem. This may be due to any of the following factors:

• Moisture trapped beneath the surface of the paint film.
• If the paint is applied over a powdery or friable surface.
• Surface contamination such as dirt, oil, and grease.
• Polish residues on the surface, which impair the adhesion of the paint.
• Excessive movement of the substrate, such as joints, imposing stress on the paint film which can result in cracking which in turn lets in moisture, ultimately resulting in a flaking paint film.
• Resins present in knots causing light coloured paints to discolour or even flake. Resin bleed and flaking is a common problem where dark colours are used on south facing elevations. This is because dark colours absorb more heat than light colours.

Putting it right

Scrape off any loose flaking and poorly adhering coating, and wash off the powdery material with clean water. The surface should then be suitable for painting when dry. If the plaster is exposed in areas, prime these areas with a thinned coat of emulsion. Follow thinning instructions on the container..

Bleeding

Cause

This is usually caused by contamination of the underlying surface by soluble stains.

Putting it right

It is important to seal the original stain by applying a coat of Polycell Stain Stop prior to re-decorating.

Cissing

Cause

This is caused by painting over contaminated surfaces such as wax, oil or polish. The paint cannot adhere to the surface and draws away leaving unpainted areas.

Putting it right

Allow the surface to dry and then rub down using 'wet and dry' abrasive paper and a solution of warm water and detergent. Once rinsed and dried the area can be repainted.

Filler shows through the paint

Make sure that all filled areas are rubbed down smooth and level. You will need to prime the filler before painting to prevent subsequent coats being absorbed more rapidly than on other areas. Use a coat of Dulux emulsion thinned 10-20% with clean water. Once this is dried you can apply a full coat of Dulux emulsion.

Foaming

Cause

Using the wrong type of roller can cause foaming of a paint film. Sponge or foam rollers should be avoided with water-based paints. Long pile rollers must be wetted out properly. Foaming happens when air gets into the wet paint film to create air bubbles. When these bubbles burst craters are left on the film surface. Sometimes these craters dry to give an even film.

Putting it right

You will need to rub down using 'wet and dry' abrasive paper using water or suitable solvent. The surface should then be rinsed and allowed to dry before repainting. If this is impractical due to the size of area affected the area could be horizontally lined with lining paper and then repainted.

Cracking of plaster

Cause

This is a common occurrence in new houses and is often the result of plaster drying out or movement of the building.

Putting it right

Cracks should be cut out and all dust and debris removed. The cracks should then be filled using an appropriate filler. The Polyfilla range has a filler for every size of gap. This can then be painted with your chosen finish.

Mould growth on exterior surfaces

Cause

Moisture is an essential element for the growth of moulds.

Putting it right

Affected areas should be treated with Weathershield Multi-Surface Fungicidal Wash. Once rinsed and allowed to dry it can be over coated with you favourite Weathershield Masonry Paint.

Painting the bricks around a fireplace

You can paint these bricks with Dulux Emulsion paint. Avoid using a matt product, as it will be soiled easily in a fireplace location, use Soft Sheen or Silk finish. Thin the first coat as directed on the container. If you want to apply a Gloss finish, prime with Dulux Sealapore primer and follow with Dulux Undercoat and Dulux High Gloss finish.

Painting over gloss on outdoor window sills

A. For painting over a gloss finish you need to use Weathershield All Seasons Masonry Paint. This is a solvent-based version of Weathershield Smooth Masonry (which is water based). A water-based product applied over a gloss finish will blister. Sand the gloss finish to ensure you get good adhesion to the surface.