Some parameters affecting the diffusion of SO42− used in iron gall ink: Preliminary findings

A systematic evaluation of the effect of components of the ink, types of the paper, temperature and humidity of environment and the direction of the paper fibers on the diffusion percentage of SO42− was made. The results showed that the diffusion percentage of SO42− was associated with all factors mentioned above. The general rule is that the higher the humidity and temperature, the greater the diffusion percentage; the smaller the basis weight of paper, the greater the diffusion percentage of SO42−; diffusion percentages of SO42− in strokes perpendicular to the paper's fiber is more bigger than ones of strokes parallel to the paper fibers.In order to estimate the age of iron gall ink entries, it is necessary to select a suitable sample, which used for comparison should be the same as those of the document in question.