Iron gall inks have a destructive effect on paper supports due to their acidic and transition metal-containing nature. For the chemical stabilization of paper-based objects, conservation studies include both antioxidant and deacidification treatments. In order to evaluate the effectiveness of the treatments, accelerated ageing experiments are performed and changes during ageing are measured. Historical manuscripts may contain colored papers and since only natural dyes and pigments were available until the development of modern chemistry in the nineteenth century, the palette was limited. Organic dyes mainly consisted of colourants obtained from plants and insects. In this study, colored papers of manuscripts from the fifteenth century which belong to the collections of Millet Library, Istanbul were analyzed via high-performance liquid chromatography. According to the results, model papers were dyed with Rheum ribes L. (rhubarb), and then an iron gall ink, prepared according to a historical recipe, was applied to them. Due to acid and transition metal content, a stabilization treatment including alkali and an antioxidant was applied on a set of samples and after 12 days of accelerated ageing, changes in pH, degree of polymerization, and optical properties of the samples were monitored. A viscometer, a useful tool to monitor the efficiency of a treatment, was employed for the determination of degree of polymerization values. Data obtained from viscometric measurements were used to evaluate the degradation rate constants of the samples. Comparison of rate constants showed that treatment had a beneficial effect.