Causes of Paint Failure on Metal
Some of the reasons of paint failure on metal are:
Paint can lose its adhesion to a metal surface and as with most of the issues below, inadequate preparation is often to blame. Specific factors contributing to this particular problem are the failure of a primer being applied before a substrate is coated in an oil-based paint or when a glossy surface has not been keyed properly.
Sometimes a coating can bubble up in blisters, so that the paint does not remain stuck to the underlying substrate. Spraying with solvent based paints in high temperatures on a surface that is too warm can lead to this problem. If coats are too thick or a coat is applied before the previous one has been allowed to dry, the solvent becomes trapped and expands which then leads to blistering.
Over time, paint film can erode causing the paint to decompose into a chalky surface layer which is loose and powdery to the touch. The chalk can also be washed down by rainwater into another area such as brickwork below cladding. This is known as chalk run-down. Either low quality paint or paint with a high level of pigmentation can lead to premature decomposition, causing chalking.
Sometimes paint can fail completely when at least one coat of paint film splits leading to cracks or flakes. Initially, the danger can be detected in hairline cracks before the flakes actually chip off. This unsightly problem is caused by inferior paint that lacks flexibility and adhesion or the coating may have been too thin. Another reason for cracks or flakes is if the surface hasn’t been properly prepared.
A painted façade can become blotched with dirty patches if debris becomes trapped on the paint film. Air pollution or soil splashed onto a surface are much more likely to adhere to a surface coated in poor quality paint.
Environmental factors such as the sun, wind and rain can cause exterior metalwork to fade prematurely especially surfaces facing the South and West. Chalking can also result in deficient colour saturation as well as tinting a white coating that isn’t intended for this purpose.
Spots of brown, grey or black mildew can appear on coated surfaces that are damp and do not receive much sunlight. Sometimes mildew can look like dirt and vice versa, but mould will spread if it is not dealt with even if it is painted over.
In order to prevent any of the problems above from happening again, proper preparation is crucial. Old coatings need to be removed from the substrate and all exposed surfaces should be primed properly before re-spraying. Our teams at Vanda Coatings prioritise preparation because we are confident this attention to detail results in a beautiful, long lasting finish. We also know it is paramount to use high quality coatings and we take great care to choose the most appropriate coating for each surface sourced on an individual basis from the best suppliers.