Combining a series of synchrotron-based techniques with Raman spectroscopy and scanning electron microscopy, we investigated 10 papyri fragments from J.-F. Champollion’s private collection. For each fragment, the carbon-black pigment found in the ink is identified as flame carbon (lampblack or soot). Using X-ray diffraction computed tomography, we show that the diffraction signal of the carbon-based pigment itself can be isolated. As a result, a contrast with the papyrus support is obtained, even in the absence of a specific chemical element in the ink. This is opening up new opportunities to decipher words written millennia ago, as part of our Cultural Heritage.