Paints and maintenance for windows
Carpenters know from ancient times that wood needs a protective layer that blocks moisture and mildew. First paints date back to before the Roman Empire, and were made with natural substances. One of the typical aspects of wooden windows and doors was the need for constant maintenance of this protective film: over the months, paint turned matt, started to crack and then flaked off. Some woods like larch, oak, iroko or teak are more resistant to weather and in some cases may be used without any treatment.
In order to avoid this damage, windows and shutters had to be removed from the wall, put on trestels, sanded and then repainted. This aging was due to polyurethane-based paints: this finish dries over time and gets damaged by sunrays. It becomes rigid and fragile and is no longer able to withstand natural expansion of wood, losing an important characteristic: elasticity. The most solid paints are lacquers, followed by dark wood stains, and then light wood stains.
Modern water-based paints, on the other hand, are more resistant and eco-friendly, because they do not contain dangerous oil-based solvants. Shutter and windows undergo special long-lasting painting cycles with minimal maintenance. A periodical cleaning with water and neutral soap is enough to remove smog and dirt; a special wood rejuvenating product restores the paint elasticity and thickness. Not all water-based paints are the same: as always, quality plays a major role.
There is a kind of wood that does not need any additional protection: we are talking of thermo-treated wood. That material is heated in an athmosphere lacking in oxygen until all humidity has gone and the wood becomes stable. It becomes lighter, darker and almost insensitive to weather and parasites because heat turns cellulose inert. At the same time, hardness and fragility increase while glues and paints tend to adhere less.
As well as its practical purposes, paint serves an aesthetic function. The surface layer can add a glossy shimmer, a matt texture, it can make the wood darker or lighter, or even completely change its colour. In some cases the underlying timber can be hand-worked in order to highlight or hide the grain, depending if one wants to preserve or remove the unmistakeable signature of this material.