The Iron Gall Ink Website

Ink Corrosion Prognosis - Why ?

Frank Ligterink, Birgit Reissland, Norbert Ligterink and Claire Phan-Tan-Luu (2010)

As a first step in conservation decision making, conservators often describe the present condition of an artifact in a so-called condition report. A condition report typically does not indicate to what extent an artifact's condition is stable or will degenerate. Thus, the urgency of preventive action remains unclear. To answer this question, the future condition of the object needs to be predicted. In other words, a damage prognosis is required.



Why are moisture and handling important?

Because exposure to high moisture and high mechanical stress levels can significantly enhance ink corrosion damage, a reliable prognosis can not be made without assessing the artifact's likely future exposure to both risk agents. Moisture exposure levels are considered high if within the next 100 years there is a significant chance (10%) of reaching a critical moisture content within the artifact. This occurs as a result of equilibration with high relative humidity levels or direct wetting, for example due to humid storage conditions, during water leakage incidents, or caused by unsafe wet/humid conservation treatments. We consider relative humidity levels arising above 70% to be increasingly dangerous with a maximum risk level at saturation. Mechanical stress exposure levels are considered high, if within the next 100 years, parts of the paper containing ink are folded or severely bend at least 10 times during consultations. Combining both environmental factors we now distinguish four different ink corrosion scenario's (A-D):



100 years
100 years + intensive handling
100 years + high moisture
100 years + high moisture + intensive handling