The improvement of mechanical properties of the paper from an old book after different restoration treatments has been investigated. It showed that simultaneous deacidification and sizing with a mixed solution of calcium hydroxide and methylcellulose provides more uniformity to the restored paper than phase treatments. Conditions of washing, bleaching, deacidification and sizing have been established in order to restore the original quality of the paper, which has also increased its resistance and durability. -- ICCROM