What defect is caused by the exposure of epoxy to ultraviolet light?

Chalking is a defect that occurs when epoxy coatings are exposed to ultraviolet (UV) light. This exposure leads to a breakdown of the polymer structure within the epoxy, which results in the formation of a powdery residue on the surface of the paint. This powdery substance is primarily composed of the degraded binder materials that have been affected by UV radiation.

As the epoxy degrades, it loses its original color and finish, which can lead to an unsightly appearance and reduced protective qualities. Chalking is a common issue with many coatings that are not formulated to withstand prolonged sun exposure, particularly those that do not contain adequate UV absorbers or stabilizers. This defect is particularly critical in applications where aesthetics and protection against environmental degradation are important factors.

Understanding chalking helps inspectors identify the effects of UV exposure on coatings and informs the selection of appropriate materials that can better endure such conditions.