Traditionally papyrus fragments are stored between glass panels in many museum collections. In most exhibits a white precipitation is formed on the inner surface of the glazing which complicates reading and digitalization. With the help of the present study the question of the origin and possibilities for avoiding these precipitations should be answered. It could be shown that the precipitations consist of the salts sodium chloride and sodium nitrate. The chloride and nitrate ions for the salt formation stem from the papyrus whereas the sodium ions are dissolved from the float glass. By the use of higher-quality glass such as borosilicate glass this process can be prevented or at least slowed down. Furthermore a storage of the exhibits at relative humidities below 70 % is recommended.