Definition of "chalking" by Brushworks Painting:In the context of painting, "chalking" refers to the formation of a fine, powdery residue on the surface of a painted area, typically caused by the degradation of the paint binder due to prolonged exposure to ultraviolet (UV) radiation, weather, and environmental conditions.
Key Characteristics of Chalking:
- Appears as a white or light-coloured powder on the surface.
- Most common in exterior paints, especially older or lower-quality acrylics and oil-based paints.
- Can be detected by rubbing your hand over the surface — if a powdery residue comes off, chalking is present.
Causes:
- UV Exposure: Breaks down the paint’s resin or binder, releasing pigment particles.
- Poor-Quality Paint: Lower-grade paints may lack sufficient UV stabilisers or durable binders.
- Over-thinning or Over-spreading: Applying paint too thinly can reduce its durability.
- Age: All paints will eventually chalk over time, especially in harsh climates like many parts of Australia.
Implications:
- Aesthetic degradation — the surface looks faded or dull.
- Can affect adhesion of new paint if not properly cleaned before repainting.
- May lead to further paint failure if left untreated.
Prevention & Treatment:
- Use high-quality, UV-resistant exterior paints.
- Proper surface preparation and application.
- Before repainting, remove chalking by washing the surface thoroughly (e.g., with a stiff brush and detergent or pressure washing), and test for residual chalking before applying new paint.
In summary, chalking is a sign of paint deterioration and should be addressed before repainting to ensure proper adhesion and a long-lasting finish.
