Reports on the work developed at the CETBGE, specifically the method and the general characteristics of the treatment. Work done on the fragments of the shipwreck from Giens, the Gallo-Roman wreck from Périgueux (Dordogne), and numerous small objects from a lake site near Paladru is described: background of the object(s) is given as well as treatment and results. Use of the lyophilazator is explained; results of woods in various states of degradation are reported. Lyophilization of objects from two sites are described with regard to background, treatment, and results. Criteria for using specific treatment methods are discussed.