Fig. 4

Graphs showing shrinkage temperatures in reference (blue bars) and aged specimens (orange bars), as well as their corresponding normalised differences (ΔT, green bars) in a ink-free parchment areas (LIG ink formulations); b inked parchment areas (LIG ink formulations); c ink-free parchment areas (LIGG ink formulations); d inked parchment areas (LIGG ink formulations). Temperature differences were normalised with respect to temperatures of reference samples. Left-hand scale corresponds to temperatures recorded in reference and aged specimens; right-hand scale corresponds to normalised temperature differences (ΔT)