Iron-gall ink corrosion: A compound-effect study

By means of design of experiments (DOE) the role of varying concentrations of the main components in iron-gall ink were investigated. The main components in the inks used were iron(II)sulphate, tannic acid and gum Arabic. In total 12 different ink compositions were made and plotted as a line on bleached softwood sulphite paper. By applying accelerated ageing and measuring the tensile strength, the contribution of each component towards the accelerated ageing of paper was calculated. It was concluded that all three main components do have an influence on the iron-gall ink corrosion process. This effect can be seen after a period of 3 days accelerated ageing at 90 degreesC and 50% relative humidity. The presence of iron(II)sulphate is dominant in the iron-gall ink corrosion process while tannic acid and gum Arabic are opposing, thus slowing down the deterioration.