The presence of fine white powder, resulting from weathering of the paint film. To fix this, Remove chalk with detergent and water. Check surface by running hand over the surface for loose powder. If chalk is still present, apply Medal Bonding Liquid, followed by Universal Undercoat.


If fading or poor colour retention is a result of chalking, remove as much of the chalk as possible by scrubbing the surface with a stiff bristle brush (or a wire brush for masonry), and rinsing thoroughly. Check for any remaining chalk by running a hand over the surface after it has dried. If a noticeable amount of chalk is still present, apply a quality solvent-based or acrylic water-based primer (or comparable sealer for masonry), then repaint the surface with a quality exterior coating. If little or no chalk remains and the old paint is sound, no priming is necessary. When repainting the surface, be sure to use a quality exterior house paint in colours that are recommended for exterior use.


Paint flaking is caused by moisture that collects behind the painted surface. To fix this, remove all flaking paint by scraping or wire brush. Prepare surface thoroughly, ensure surface is dry and clean. Once the surface is free of all dirt, you may paint.


The formation of dome shaped, hallow projections of paint. Results from localised loss of adhesion. To fix this, Remove source of moisture e.g. dripping air-conditioner, remove blisters and allow surface to dry, prepare the surface and paint.

Nail head rusting

Rusting of metals is a case of metal oxidation. Iron will oxidize to form rust. Water will cause metals to rust – the reaction can be accelerated by adding salts. In the corrosion process metals are oxidised. Reddish, brown stains on the paint surface. To fix this, sand off rust, countersink the nails, prime the spots and ensure no gaps around the nail before painting.


Alkali attack on the binder paint and usually takes the form of blisters on the paint film. To fix this, remove deteriorated paint film by scarping or wire brushing, remove source of moisture e.g. leaking air-conditioner, prepare the surface and paint.

Poor gloss retention

A deterioration of the paint film may result in excessive or rapid loss of lustre of the topcoat. To fix this, use products according to the specification. Use good quality paints for extended durability. While all types of paint will lose some degree of lustre over time, lower-quality paints generally lose their gloss much earlier than better grades of paint.

Grin through

This refers to the exposure of the previous coating or the substrate through the top coat of paint. To fix this, Always follow the spreading rate quoted for the product, always apply two coats of top coat (If three were stipulated) and use a good brush/roller for application.


Distinct vertical patterns usually a result of poor paint application. These are often roller markings on large surface areas. To prevent this, adopt correct application technique, roll back over thick lines on the wall while they are wet, to smooth the paint and ensure uniformity, always mix paint thoroughly and during use if necessary and apply the product according to the specification.


The splitting of a dry paint film or varnish film, usually as a result of aging or movement of the substrate or the previous coating. To fix this, remove loose or flaking paint with a wire brush or scrapper and prime bare areas adequately before painting.


Crinkling of a paint coating on drying. To fix this, remove wrinkling paint by scraping or sanding, prime the substrate with a suitable Medal primer, Ensure the primer is dry and paint your topcoat with a quality product. Do not apply too thick a coat of paint.

Mould / mildew

Grey-brown – black areas on the surface of a paint coating caused by the presence of micro organisms. To fix this, use house hold bleach to kill the micro-organisms. Remove mildew by scrubbing the surface with a dilute solution of household bleach. Wear suitable protection (gloves, eye protection, mask). High pressure cleaning is also a cleaning option. Prime surface appropriately with Medal primer and top coat with a quality product.


Uneven paint colouring on a painted surface. Always prepare surface adequately before painting. Remove the previous paint if necessary. Always smooth out filled areas and prime well. Apply primer to the wall, using steady, short strokes with a well-wetted brush or roller, covering the previous coat of paint especially if the new coat is lighter than the previous coat. Clean and dry the brushes before applying top coat, wet brushes will cause patchiness through dilution. Apply the topcoat with steady and even strokes.


Appearance of a darker shade in areas where application areas overlap. Always maintain a wet edge to “work” paint across the substrate. Maintain a wet edge by applying paint towards an unpainted area and then back onto a freshly painted section. Work quickly to ensure that you’re always lapping a new layer of paint onto paint that is still wet. This technique (brushing or rolling from wet to dry, rather than vice versa) will produce a smooth and uniform appearance. Keep the area you are working on to a manageable size, and plan for interruptions at a natural break, such as at a window, door or corner.

Alligatoring / mud cracking

A scaly pattern that appears on paint due to the inability of the paint to bond to a glossy coating beneath. To fix this, old paint should be completely removed by scraping and sanding the surface; a heat gun can be used to speed work on large surfaces, but take care to avoid igniting paint or substrate. The surface should then be primed with a high quality water-based primer, then painted with a quality exterior water-based paint.

Cratering / foaming

The formation of tiny bubbles resulting in depressions (craters) on the paint surface when these tiny bubbles break. To fix this, sand problem areas down before painting. Ensure that surfaces are well prepared prior to painting. (All paints will foam to some degree during application. However, higher-quality paints are formulated to ensure that the bubbles break while the paint is still wet, allowing for good flow and appearance)

Dirt pick-up

This refers to the accumulation of dirt on the painted surface, may resemble mildew. Clean dirty areas by washing with a mild soap solution. To fix this, use a scrubbing brush if dirt is stubborn. Use a good quality paint, which usually has good dirt shedding properties. Avoid textured products for high pollution areas. (Sheen products offer good dirt shedding)

Tannin bleeding

A brownish discolouration of a paint as a result of migrating tannin from certain wood substrates through to the paint film. To fix this, remove source of moisture, remove damaged paint film by scraping, sanding or wire brushing, ensure that the substrate is sufficiently dry, apply a suitable Medal primer and paint.