In restoration workshops various bleaching methods are used. One of these methods employs a mild bleaching agent, chloramine T. Often this technique is used without rinsing after bleaching. Research was initiated in order to find out whether the residues of this bleaching agent add to the deterioration of the paper. In order to compare the results properly some other standard bleaching methods were included in the research. Three kinds of paper were treated with the various bleaching methods, aged by heating and tested on folding endurance, whiteness pH and degree of polymerization. From these tests it was concluded that residues of chloramine T are indeed dangerous for paper. Another important observation is, that rinsing with water, gives more strength to paper.