Deposits on the inner sides of glass plates used to encapsulate papyrus and parchment fragments were investigated. By analytical examination, the inorganic constituents of the deposits were identified as sodium chloride; additional organic components were identified as vegetable proteins. Migration of water-soluble constituents from the encapsulated fragments to the inner surface of the glass plates seems to be caused by strong fluctuation in the microclimate as a consequence of variations in the temperature on the outside of the encapsulation.