Leonardo da Vinci pioneered a conservation technique (proof, in the Madrid Codex)

They are known as the Madrid I and II Codices : they are several manuscripts by Leonardo da Vinci that arrived in Spain with Pompeo Leoni , sculptor to Philip II , and that, after 150 years of being lost, were found in 1964 in the archives of the National Library . Well: in the Madrid II Codex, on the right-hand side of folio 87, a team of researchers has noticed a note that until now had gone largely unnoticed. "They will be better preserved if the bark is removed and they are burned on the surface than in any other way," Da Vinci writes on that page.

Renaissance expert Annalisa Di Maria , molecular biologist Andrea da Montefeltro , and art historian Lucica Bianchi have conducted an in-depth study of the subject and concluded that Leonardo's words were revolutionary. Until then, wood preservation methods had been largely passive: it was known, for example, that the wooden piles that support Venetian buildings slowed their decomposition when submerged in water. Leonardo, however, proposed an active intervention : modifying the properties of the wood through direct manipulation, specifically surface carbonization.

"His idea anticipated by more than two centuries the Japanese process of Shou Sugi Ban (or Yakisugi), documented only from the 18th century onward," the study's authors argue. Shou Sugi Ban is a Japanese technique that involves charring the surface of wood to protect it from insects and fungi.

The Renaissance genius intuited principles that today underpin materials science and sustainable bioarchitecture : the same treatment that Leonardo suggested for preserving posts, beams, and gears is adopted today by contemporary architects for cladding, facades, and ecological design.

It's important to keep in mind that for Leonardo, wood wasn't just any old material . During the Renaissance, it was the basis for bridges, ships, machines, and musical instruments. The Madrid Codex, in fact, reveals his interest in every aspect of this material: from the characteristics of each type of wood to its use in architecture , and even its use in the creation of musical instruments.

Researchers rule out the possibility that Leonardo was familiar with Japanese practices, since between the 15th and 16th centuries, Japan was virtually isolated and yakisugi was not yet documented. The coincidence is therefore extraordinary: two distant, uncontacted cultures found the same technical solution to a common problem, a phenomenon known as convergent invention. However, some researchers wonder whether the cultural exchanges initiated in the 16th century by Portuguese and Spanish navigators could have brought indirect traces of Leonardo's ideas to the East. It is a hypothesis.

Leonardo’s entry on page 87 of the Madrid II Codex didn’t come out of nowhere. The book bears witness to his interaction with such great ancient authors as Pliny the Elder , who described the characteristics of natural materials in his Naturalis Historia ; Vitruvius , who offered advice on the timing and methods of woodcutting in his De Architectura ; and Rutilius Taurus Aemilianus Palladius , a Roman agronomist who analyzed forest cultivation and conservation.

The note about burning wood does not appear in any ancient author; it represents an original idea, the result of experimentation.

“ Leonardo , an 'omnivorous reader,' didn't just copy: he compared these sources, highlighted their differences, and integrated them with his own practical observations. This is precisely where his genius emerges: the note about burning wood doesn't appear in any ancient author, but rather represents an original idea, the fruit of experimentation,” the researchers responsible for this study state.

Surface charring of wood is now known to produce three fundamental effects . First, it makes it waterproof and weather-resistant , as fire eliminates residual moisture and closes the wood's pores. The charred layer thus becomes a barrier against water and climatic variations. Second, the technique acts as fire protection because, paradoxically, wood that has already been charred on the surface resists flames better because the carbon layer slows the spread of heat. And finally, it is a method that kills insects and fungi , as heat eliminates the sugars and nutritional components of cellulose, making the material inhospitable to parasites and mold.