One of the most popular methods of monitoring the mechanical properties of paper with aging is DP measurement.Viscometer is a useful tool for the determination of degree of polymerization values. Data obtained from viscometric measurements are used to evaluate degradation rate constants of the samples. But The usual criticism of viscometry in studies like dyed paper is that it doesn't appropriately take into account the error that could arise from instability of the most degraded and oxidised cellulose affected by ink.