Effect of Aqueous Treatments on Nneteenth-Century Iton-Gall-Ink Documents: Assessment Using Hyperspectral Imaging

Presented at the Book and Paper Group session, AIC 37th Annual Meeting, May 20–23, 2009, Los Angeles, California. tested by exposure to heat and humidity, highintensity light, and elevated humidity at room temperature. Changes were evaluated against unaged or untreated controls. Methods of evaluation include hyperspectral imaging, color measurement, pH, iron (II) testing using bathophenthroline test strips (Neevel and Reissland 2005), and microfade testing. Some of these results have been previously reported (Tse et al. 2006). Hyperspectral imaging combines spectroscopic information with the spatial information of the sample. In hyperspectral imaging spectral information is collected in narrow bands (10 nm) that are contiguous. In this sense spatial information about an object is obtained in two dimensions (x, y) and spectral information is obtained in a third dimension (z), which allows the storage of information in a threedimensional data cube. The important advantage of using hyperspectral imaging is that an accurate digital record can be acquired of an historical object (Kubik 2007). This makes it a very powerful technique for identifying and mapping pigments in paintings (Berns 2002; Baronti 1998). For written documents hyperspectral imaging has been used for enhancing the legibility of faint text (Goltz 2007), as well as revealing text that was over-written with another ink (Attas 2004). This paper highlights the usefulness of hyperspectral imaging and image analysis techniques to evaluate the effect of aqueous treatments on iron-gall ink.