Stability and Degradation Issues of Manganese Violet Pigment in Polymeric Paints: Morphological and Chemical Changes Under SO2 and Humidity Exposure
Year: 2025
Type: article
Abstract: This study focuses on investigating the stability of modern and contemporary paints based on manganese violet pigment PV16 (NH4MnP2O7) when exposed to atmospheric pollutants, specifically sulfur dioxide (SO2) in the presence of high relative humidity. In particular, this study aims to investigate the role of PV16 in increasing the degradation processes of various modern binders. Therefore, the objectives of this research can be divided into (i) evaluating the chemical modifications involving PV16, (ii) investigating the degradation processes that occur in different organic matrices (i.e., drying oil, alkyd resin, and acrylic and styrene–acrylic emulsions), and (iii) comparing the chemical stability of model and commercial paints. The paints were analyzed by 3D Optical Microscopy, Attenuated total Reflection–Fourier-Transform Infrared spectroscopy (ATR-FTIR) and μ-Raman Spectroscopy, Scanning Electron Microscope coupled with Energy Dispersive X-Ray spectroscopy (SEM-EDX), X-Ray Powder Diffraction (XRPD), Fiber Optic Reflectance Spectroscopy (FORS), Pyrolysis–Gas Chromatography–Mass Spectrometry (Py-GC/MS), and Thermally assisted Hydrolysis and Methylation (THM) of Py-GC/MS (THM-Py-GC/MS). The results show that when exposed to high relative humidity and SO2, PV16 presents a colorimetric change from violet to grey; several compounds crystallize on the surface; and, depending on the binder, various degradation reactions occur. This study highlights the susceptibility of manganese violet pigment PV16 under certain environmental conditions, which may be considered to define adequate conservation strategies for works of art containing this specific pigment. Additionally, the results obtained within this investigation point out the need to expand the chemical knowledge of this material for engineering, sensing, and industrial applications.
Source: Applied Sciences
DOI: 10.3390/app15094630
Language: English
Subfield: Archeology
Field: Arts and Humanities
Domain: Social Sciences
Open Access status: gold
Estimated APC paid: $2,896
OpenAlex ID: W4409658744