Sherlock: The most plausible explanation is that the ink was removed chemically after the manuscript was produced, leaving the underlying fibers to show the inked letters as faint, almost transparent strokes. It's a trick often used to hide information while keeping the text legible to a trained eye. Alternatively, someone could have printed the text with a faint, invisible ink that only shows up under a certain wavelength, so the "missing ink" is really just invisible to the naked eye. The trick is sophisticated but not impossible for a skilled hand.

Sherlock: A modern lab can use spectroscopy, chromatography, and X‑ray fluorescence to detect trace residues of pigment or binding agents, even if the bulk ink has been removed. If the ink was never applied, the paper will lack those signatures entirely. So yes, they can distinguish between removal and absence, but only if the sample is preserved correctly.