EN
Paper dating from 1856 was bleached by means of three different methods, with sodium boronhydride, chloraminę T with sodium tiosulphate and chloraminę T with sodium boronhydride as anti-bleaches. After the bleaching, the paper was deacidified with a solution of Са(ОН)г and structurally reinforced with methylocellulose. Accelerated ageing 105°C for 24 nights and days) enabled to examine: the degree of whiteness, yellowness, pH of the water extract, tearing load and the number of double folds. It was found that the sodium bronhydride has a positive impact on the durability of the paper. The sodium bornohydride also proved to be a better anti-bleach than the sodium tiosulphate after chloraminę bleaching. On the other hand, the small growth of whiteness obtained in the course of research questions the purposefulness of using sodium boronhydride as well as probably other derivatives as bleaches. Fig. 1. Alterations of the whiteness of paper during ageing in 105°C A — unbleached В — bleached with NaBH^ С — bleached with + Na2 S2 O3 D — bleached with + NaBH^ Fig. 2. Alterations of load which tears paper during ageing in 105°C Fig. 3. Alterations of the number of double folds during ageing in 105°C