The role of the library is an essential one, that is to be accessible and to communicate information. The information is given to us through its documents. In addition to this first role of communicator, the library also has another essential role, namely to preserve the documents it holds, so that they can be passed on to future generations. The funds in libraries and archives are extremely fragile, due to the varied support of organic material from which they are made: paper, cloth, leather and adhesives. These organic substances are subjected to a continuous and inevitable aging process, caused by endogenous and exogenous degradation factors. Documentary heritage is most often preserved under improper conditions, which leads to its definitive destruction. In most cases, preservation measures are taken late, when nothing can be done to save it.