There are various methods for drying wood, and we will examine underwater drying.
Underwater drying is a method in which logs are submerged in water for about six months to a year, and then the logs are removed from the water and dried again for about six months to a year.
Submerging the logs in water causes changes in the properties of the tree, as sap components and debris in the tree are released into the water, making it easier for water to escape. The lumber used for the rebuilding of the Ise Jingu Shrine and other shrines every 20 years (shikinen sengu) is left in the water as logs for three years.
The water is removed from the logs simply by lifting them out of the water and leaving them standing, but it takes another six months to a year to settle the wood down to the point where it can actually be used as a material.
The underwater-dried lumber, which is soaked in water once and then dried, retains just the right amount of nutrients and allows the binding water to drain out without destroying the wood fibers, making it very difficult for the lumber to crack or shrink later on.
In the old days, loggers used to make rafts from logs in the mountains and transport the lumber down rivers, not only for logistical reasons, but also because it was a wonderful method of transportation that combined the drying technique of soaking in water, which was practiced in ponds and swamps all over the country.
While underwater drying is a wonderful technique and an excellent drying method that is gentle on the wood, it is the most time-consuming drying method and requires a lot of space in ponds and drying areas.
Waterlogged logs are said to be 1.5 times heavier than normal logs and cannot be moved by hand, so tow trucks and other vehicles are needed. This is a very small effort, but it is a very effective way to use submerged drying in woodworking.
Although it is only a small effort, I would like to introduce the underwater drying technique to woodworking and pass on the wonderful Japanese technology filled with the wisdom of the ancients, if only a little.