Since ancient times, wood has been one of the best known and most used materials in the world.

Being a transformable and highly adaptable material, it helped to start man’s first technological processes: it was the first simple machine, i.e. the lever (partridge stick, wedge, bow), the first complex machine (plough, loom, mill ), the first means of transport (sleighs, carts, rafts), the first source of controllable energy (for cooking food, heating but also for craft activities such as ceramics, metallurgy, etc.).

Wood has also always been used for artistic purposes. The surfaces can be more or less smooth, natural colored or impregnated, varnished, lacquered, gilded or painted.
Wood is therefore one of the most tested materials and, despite being of organic origin, with its properties it defies the centuries and millennia.

You will be surprised to know that, even for a very wide range, wood is not very sensitive to sudden changes in temperature between 1 and 65 degrees. The real problem is given by humidity, which being closely related to temperature, makes it an important parameter to control. In fact, we know that as T increases, relative humidity decreases and vice versa. The reason why moisture is one of the biggest threats to wood is that it is a hygroscopic material.

Consequently, wood absorbs or releases humidity in an attempt to maintain equilibrium with the relative humidity of the environment in which it is exposed and, when the climate changes, shrinkage and swelling occur. The continuous succession of these phenomena, to which we do not pay much attention especially in closed houses, leads to the appearance of cracks and splits in the wood or more or less evident deformations.

Furthermore, there is another aspect that is less intuitive but which, if we have artefacts covered in polychromes to protect, makes the question even more delicate, and all the more reason it becomes more important to pay the utmost attention to the question of the dry-humid environment.

Wooden artifacts and their paints or varnishes applied as decoration or to protect the wood, behave differently with respect to changes in humidity in the environment. If wood tends to swell when it absorbs moisture, paint and varnish behave in the opposite way, i.e. they tend to shrink. Conversely, when the wood shrinks because the environment becomes drier, the paints and varnishes expand. We can then guess that the paint will be easier to crack and detach from the support.
The ideal parameters for the correct conservation of wooden artefacts can be widely found in the literature, which agree in establishing the relative humidity at around 50% and a temperature at 20-22°C. However, it is important to understand that the greatest attention must be paid to the sudden variations and short-term fluctuations that wood may have to undergo, because an object can adapt over time to the environment in which it lives and with which it enters into balance, but it can never adapt without consequences to changes in the environment.

You can find the full article at