The restoration of Giacomo Balla’s Ritratto d’uomo / Eugenio Riva has unveiled unexpected insights into the intersection of historical restoration practices and modern scientific techniques. This study documents the discovery and analysis of onion residues on the painting's surface, attributed to a mid-20th-century cleaning attempt. Leveraging cutting-edge analytical tools—such as FTIR ATR spectroscopy, SEM/EDS, and UV imaging—researchers explored the chemical and morphological effects of this unconventional treatment. Additionally, the article highlights innovative solutions, including enzymatic cleaning formulations and polar solvent systems, which were employed to safely restore the artwork. This multidisciplinary approach not only restored the painting’s aesthetic coherence but also contributed to the broader understanding of restoration challenges posed by historical interventions