Evaluating the effects of treatments on iron gall ink corroded documents - A new analytical methodology

The development of a suitable conservation treatment for ink corrosion requires a thorough evaluation of a large number of model papers and inks as well as originals. While the currently used bursting strength evaluation gives an estimate of failure of documents along the corroded ink lines, in real-life situations, its repeatability is low and numerous measurements need to be performed to obtain a reasonably reliable value. It is suggested that model iron gall ink corroded papers may also be studied using viscometry, which is a simple, reliable method requiring only a small amount of sample. For original documents, where sampling for accelerated ageing is very restricted, scanning device assisted brightness determination of the verso of the writing is proposed for the evaluation of the effects of conservation treatment on paper during accelerated ageing. However, several parameters influencing colour formation and evaluation on the verso, including the rate of migration, paper density, surface furnish etc., prevent the method from being used to compare different papers before these effects are fully assessed.