Chalking happens to the best of us, or even the best painted surfaces. In fact, it’s a natural part of the paint lifecycle. You will find some chalking can happen over time; however, it can be accelerated due to a few reasons. Six to be precise.
1. Use of dark colours
Dark colours absorb more heat and UV radiation than lighter colours which causes great stress on the paint. Just as stress ages us humans (not written by AI technology), the same can be said for your paint. This fascinates us.
Fun fact: Chalking is more obvious to spot on darker colours than light ones.
2. Sunlight & UV Radiation
Just like how a day in the sun can cause a nasty sunburn, UV radiation and sunlight affects painted surfaces in a similar way, Chalking can occur at an accelerated rate in exterior environments where the painted surface is fully exposed to high levels of sunlight over an extended period.
3. Wrong product
Thinking of saving money and using your interior paint for your next outdoor paint project? Think again. Using the wrong product on your paint project can be a cause of chalking. For example, oil based enamel paints if used on an exterior surface, will likely lose their gloss and become powdery over time. That’s why we should always get the specific product for a specific environment – your driveway needs concrete paint, while your bathroom or basement is better off with a waterproof paint.
4. Incorrect film thickness
Everyone makes mistakes. Applying the product at lower than the recommended film base can accelerate the process of chalking. Also, if chalking occurs prematurely or inconsistently, this indicates that there may have been some irregularity during the application. This results in fluctuations in the applied film build, leaving some spots more susceptible to early degeneration.
Incorrect film thickness is usually a result of a workmanship or application issue.
5. Coastal environments
Living by the sea shouldn’t make you feel blue, but a mixture of salt and atmospheric moisture can create a corrosive environment, resulting in chalking. The constant exposure will result your painted surface showing signs of deterioration more quickly than expected.
6. Hot/Cold Temperature:
This is where the Goldilocks principle applies. If the temperature and UV radiation is too hot or cold, it can result in chalking. The greater the extremes of the UV radiation and temperature, the bigger the stress on the coating system is.
Solution:
Rub the surface of the paint with a finger or a dark-coloured cloth to determine the degree of chalking. Dampen the chalking area and scrub with a detergent based wash and cloth, sponge or broom. Once cleaned and dry, rub the surface again with a dark-coloured cloth to check if all residue has been removed. If the cloth shows no residue, wipe the surface once more with a clean damp cloth and it will be ready for repainting (if it also passes a cross-hatch adhesion test).
Prevention:
Some ways to minimise or delay the onset of chalking include:
- Make sure to apply paint products and coating systems that are acknowledged by the manufacturer to be UV resistant.
- Select lighter colours for your paint project as they tend to absorb less heat and UV radiation.
- Select colours based on oxides and/or inorganic pigments which are generally more UV resistant.
- Establish a maintenance procedure from the initial stages of your project to ensure that the painted surfaces are washed annually and repainted within a predetermined period of time to maintain their good condition.