In preservation of old and painted wood, before and after to put in opera, with the pourpose of prevention and control (stop) of degradation and deterioration evolutive effects we use a large range of procedures, mechanical, chimical, thermical and radiative typs. The most recent used procedures are: laser clining, penetration by imersion or vacuum, gasing, inert helium or nitrogen, skinning or impregnation etc. Most times we use procedures with multiple effects: climate, chemical, microbiological, photochemical and phisico- mechanical or structural stabilization protection. Elected treatments must to be compatible in terms of new materials and application procedures with the put into opera old wood. In this sense, to follow a preliminary study of compatibility or rendering compatible of treatment with artifact, commonly used artificial aging methods. In the case of precolaps supports are used a number of direct interventions (restorative synthesis of duplication processes, casting or molding directly on the painting, using paper pasta for support and modeling materials for ornaments, colors activation by chelating), and indirect (completions by the attachment, adherence or adhesive of structural and functional elements obtained separately and making scientific replies (Sandu, I, 2006). Selection of materials for intervention takes account of physical and chemical nature of the artwork, its conservation condition, the patrimonial value of keeping climate conditions (Sandu, IG, 2006). Procedures and materials are chosen with a minimum action to the object of art and reversible and which respects the principles of integrated conservation and stylisticaly restoration. Interventions necessary for active preservation derived from the casuistry of conservation status, being a best intervention protocol established by a plurality of proposals interdisciplinary of a team of specialists from various fields, which can not miss the conservative, the art historian, the architect engineer in the wood industry and cellulosic materials, etc. The materials engaged are in fact physical and chemical systems, grouped in cleaning systems / physical cleaning, biocide treatment systems, consolidateds inorganic and organic, physical and structural reintetgrateds, color and aesthetics, pellicle with protective climatic, mechanical and physico-chemical properties, vernes or lakes, etc. This paper presents the latest procedures and methods of preserving the art object of old wood polychrome, and a study on the behavior of various species of wood in the process of hydration and dehydration.