Since ancient times, wood has been one of the best known and most widely used materials in the world. Being a transformable and highly adaptable material, it helped start man's first technological processes: it was the first simple machine, i.e., the lever (pernickety stick, wedge, bow), the first complex machine (plow, loom, mill), the first means of transportation (sledges, wagons, rafts), the first controllable source of energy (for cooking food, heating but also for craft activities such as pottery, metallurgy etc.). Wood has also always been used for artistic purposes. Surfaces can be more or less polished, naturally colored or impregnated, varnished, lacquered, gilded or painted.

Thus, wood is one of the most experimented materials and, despite being of organic origin, with its properties it defies the centuries and millennia.

It will surprise you to know that, even over a very wide range (between 1 and 65 degrees), wood is not very sensitive to temperature. The actual problem comes from moisture: since moisture is closely related to temperature, it becomes important to control also the temperature. In fact, we know that as temperature increases, relative humidity decreases and vice versa. The reason why moisture is one of the greatest threats to wood is that wood is a hygroscopic material. Consequently, wood absorbs or releases moisture to maintain equilibrium with the relative humidity of the environment, and when the climate changes, shrinkage and swelling phenomena occur. The continuous succession of these phenomena (which especially in indoor dwellings we do not pay much attention to) leads to the occurrence of cracks and splits in the wood or more or less visible deformations.

In addition, there is another aspect that is less intuitive but, if we have artifacts covered with polychromes to protect, makes the issue even more delicate. Wood artifacts and their paints or varnishes (applied as decoration or to protect the wood) behave differently with respect to changing humidity in the environment. If wood tends to swell when it absorbs moisture, paint and varnish tend to shrink. Conversely, when wood shrinks as the environment becomes drier, paint and varnish will expand. We can guess then that the paint will be facilitated to crack and detach from the substrate.

Ideal parameters for proper preservation of wooden artifacts can be found widely in the literature, which agrees in establishing relative humidity at about 50 percent and a temperature of 20-22°C. However, it is important to understand that the greatest care must be taken in the abrupt changes and short-term fluctuations that wood may experience. In fact, an object may adapt over time to the environment in which it lives and with which it comes into balance, but it will never be able to adapt without consequence to changes in the environment.

Therefore, it is very important to control the hygrometric conditions of the environment in which the artifact is stored. Very often, however, this habit is completely lacking in collectors' homes or exhibition spaces, and generally even less thought is given to the importance of monitoring parameters when transporting wooden objects. Indeed, it is during movement from one environment to another that wooden artifacts experience abrupt environmental changes with irreversible consequences. That’s why when these objects are moved for restoration purposes, the hygrometric conditions should be checked both at the place where the restoration is carried out and at the place of destination. It is not uncommon for the returned artifact from a restoration to crack once it is re-established in its environment. When similar conditions cannot be created at the destination site, then the object should be gradually acclimated to its new environment.