The effect of different strengthening methods on different kinds of paper

Five different papers, three old ones, as they might be the object of a strengthening treatment in the restoration workshop, have been strengthened according to four different relevant treatments (or six, as one of them was used in three variants), submitted to accelerated ageing and checked for the strengthening effect, its stability and for change in aesthetic appearance. All methods, namely splitting using different adhesives for the core, overall strengthening in the leafcasting machine, lamination using a heatset acrylic and Parylene coating, gave sufficient strength to the papers, Parylene coating with the alarming exception that it provokes enhanced decay during accelerated ageing of groundwood paper. The impact of the different strengthening methods is depending on the kind of paper. Leafcasting seems to be best apt for old, Parylene coating for modem supercalandered and coated paper. As one of the methods, i.e. overall strengthening in the leafcasting machine is not very well known in the conservation community, a more detailed description is given to explain the procedure.