Chalking is the fine powder that forms on a painted surface. A small amount of chalking on a newly painted surface is not a concern. But excessive or continual chalking is a bad sign.
The Causes of Paint Surface Chalking
Chalking is caused by one of the paint constituents breaking down. This breakdown can be caused by several situations as shown:
- If the paint is thinned too much it will tend to chalk into fine powder.
- Cheap paint that is already too thin will tend to chalk
- A porous surface will soak up paint, or part of the paint constituents, and soon start to chalk. This is common with surfaces that have not been given a primer/undercoat.
- A dirty surface can cause chalking. This tends to occur with other problems like blistering paint.
- Strong ultraviolet light (UV) or long-term exposure to UV will cause the paint to break down, leading to colour fading and often causing chalking.
- Some solvents will cause chalking if left on the paint surface. This includes stronger cleaning solvents.
- Coastal environments, with moist salty air, tend to have more chalking problems than stable dry environments.
How to Reduce Paint Surface Chalking
As mentioned newly painted surfaces tend to have a little chalking, which is not an issue. By following these steps you can ensure that your new painting project will have fewer chalking issues.
- Choosing a quality paint
- Applying a good quality primer to a well-prepared surface.
- Not thinning paint for external application.
- Applying lighter colours that are less UV absorbent.
- Using inorganic pigment colours that do not react strongly to UV.
- Regular washing and cleaning of external paint will greatly reduce chalking problems.
A surface that already suffers chalking will eventually need to be repainted. Clean the chalked surface with Trisodium Phosphate and wash it with water. Repaint when the surface is completely dry.
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