Moon wood – Wood harvested at the right time

For thousands of years people have been preoccupied with how the time of year when a tree is felled influences the quality of the timber. Felled wood is particularly strong and hard-wearing during a waning moon and when there is a new moon.

Eiche Mond Foto: Rachele Z. Cecchini - Foto: Rachele Z. Cecchini - Thoma Wood100

Foto: Rachele Z. Cecchini

It’s not only the trees themselves that are able to reach ages which can exceed ours by a hundredfold: their wood can last undamaged for incredible periods of time. Take for example the wooden temples in Asia, which have survived not only centuries, but close to two millennia. Artfully built by Buddhist monks out of enormous tree trunks, such human monuments reveal all of the possibilities which lie hidden in trees.

But how does wood become a material which can withstand the toll of thousands of years of weather unscathed? Three things are responsible for making wood particularly durable. First, choosing properly grown trees; second, harvesting the wood at the right time, and, third, correctly storing, drying and processing the wood. In this section we would like to look at the harvesting time in more detail.

The sap being at its lowest and harvesting during a waning moon form the golden thread, which weaves its way through the historical relationship between man and trees. From Julius Caesar, to Pliny the Elder, to Theophrastus, there are records and reports of how trees were harvested only when the moon was waning. The proper felling time was known about in the Middle Ages and the Renaissance too. The fact that the same lunar rules crop up time and time again naturally gives the topic a lot of weight. Still, it’s not scientific proof.

In 2003 a small research team at one of the most prestigious, technological universities in Europe, ETH Zurich, worked to establish a scientific proof. Prof. Ernst Zürcher conducted a research project which initially investigated the relationships between rhythms in time and plants in a broad context.

It was observed that the way beans swelled in water is not always the same, but in fact corresponds to the rhythm of the moon. As the moon waxes, the beans soak up more water, and as it wanes, they “drink” much less in the same time. The germination of seeds of different trees and plants was investigated as a function of the rhythm of the lunar phases. It was shown that the germination rate, germ rates, mean height and height of the plants correlate with the lunar phase after four months. A further investigation revealed that trees pulse exactly in time with the tides of the oceans as governed by the moon. When the moon is waxing, the trunks expand. When the moon is waning, they shrink again. The diameter of the trees grows and shrinks in rhythm with the ebb and flow – only by a few hundredths of a millimeter but measurable nonetheless.

The direct weathering tests carried out on wood samples, which were evaluated as part of the study at the ETH Zurich, were however decisive in proving the influence of the moon on construction timber. In the actual weathering test, in which a large number of mushroom spores collectively worked away on the wood, Prof. Zürcher investigated the validity of the old tree felling rules and was able to establish for the first time that moon wood is more durable and more resistant to weathering than conventionally harvested wood. In addition, he was also able to explain an important part of the underlying principle.

He discovered that water in wood is something quite different to water in a glass. The connection of the water and the wood cells, the movement of the liquid within the honeycomb pattern, cascades and the finest capillary tubes are subject to numerous physical influences. For example, water in the very finest of capillary tubes can assume a gelatinous aggregate state and remain liquid up to -15°C.

Moon wood, harvested during the waning moon, has more bound water in its interior. This means that it contracts more tightly during the drying process, it only shrinks to a marginal degree. This makes the wood denser, more resistant to compression and also more resistant to invasive fungi, insects and voracious flames. The advantage moon wood has in terms of density ranged from 5-7% over several thousand samples. From a technical point of view, this is a significant improvement compared to “non-moon wood”.


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