Paint microplastic formation from existing structures

Coil coatings are high-performance organic coatings used for many applications, primarily for exterior architecture such as facades, roofing, and rainwater systems. In this process, large metal coils (typically aluminum or steel) pass through a series of fully automated production lines. The applied organic coatings are generally thinner than post-applied paints but consist of multiple layers to prevent corrosion and enhance weather resistance and durability. A coating is composed of resins (polyesters, polyurethanes, etc.), pigments, solvents, and additives combined in various ratios. Normally, these materials are designed to withstand very harsh conditions. However, factors such as UV radiation, high humidity and temperature, prolonged exposure duration, and the chemical composition of both coating and substrate significantly influence their degradation.

Most studies place samples in artificial weathering chambers, which cannot fully replicate the complex interplay of environmental processes. As part of the degradation process, the formation of microplastics is expected. Paint particles are often overlooked or misclassified within the broader category of micro-debris. However, recent findings indicate that paint-derived particles can constitute a significant portion of microplastic pollution.

In this research, samples were collected from the external surface of an existing building made with coil-coated panels and analyzed in the laboratory. The techniques used for microplastic analysis were a stereomicroscope for optical observation, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy for chemical analysis, and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS) for elemental analysis and surface morphology characterization. This research aims to investigate the causes of microplastic formation, analyze their properties, and better understand their contribution to pollution, leading to the development of reduction strategies. Paint particles were detected in most collected samples, with spectroscopic analysis identifying many as polyester-based materials. A more systematic sampling approach is needed to determine all environmental processes affecting the degradation of existing structures.