<p>This study aims to understand the mechanisms of deterioration and the side effects of carbon ink on papyrus manuscripts, which are essential for developing effective preventive and intervention strategies. The impact of carbon ink on various properties of papyrus sheets—including morphological, mechanical, and chemical characteristics—was examined. Some un-inked and inked papyrus samples were prepared and subjected to accelerated heat and light aging processes to produce aged samples comparable to archaeological specimens for analysis. Several analytical techniques were used, including a digital microscope and a Scanning Electron Microscope (SEM), color measurement with a spectrophotometer, assessments of mechanical properties such as tensile strength and elongation, and elemental analysis through EDX. Chemical changes in the samples were evaluated using X-ray diffraction (XRD) to determine the crystallinity index and ATR-Fourier transform infrared spectroscopy (ATR-FTIR). The results showed that carbon ink affected the properties of papyrus sheets. Notably, inked samples exhibited a significant color change compared to un-inked samples. Mechanical properties, including tensile strength and elongation, decreased, and the crystallinity index also declined. XRD analysis indicated increased cellulose crystallinity in un-inked papyrus samples, whereas inked samples did not show this increase. Additionally, ATR-FTIR analysis revealed chemical changes in the inked papyrus, particularly oxidation of the fibers.</p> Graphical Abstract