I recognize that confirmed theories are superior to unscientific thoughts that pass through generations. However, common sense counterbalances scientific theories with local, indigenous knowledge, both of which are crucial in maintaining the environment.
While I was conducting research in Jepara regency, Indonesia, under the auspices of Bogor Agricultural University and ACIAR-CIFOR, I found an outrageously odd thing about the set theories I had studied. This thing is perhaps unique to Jepara regency. It has persisted for many years and is a characteristic of Jepara’s wooden furniture industry, namely wood drying.
As we know, in studying wood technology, there are two wood-drying methods — conventional and natural. When I was in Jepara, I saw a different method used for drying wood products. I determined that the method is, however, well known, and is called smoked wood drying. Not only food but also wood can be dried with smoke from burning wood waste.
I was so astonished and shocked, thinking that smoke drying would cause defects in wood products. Negative thinking and questions murmured in my mind, blaming the local and indigenous knowledge of Jepara’s furniture industry for being so deviant. However, I should have been considering and respecting the knowledge due to being a forestry academician. Furthermore, due to being born in Jepara, I should have been clarifying whether the method was scientifically proven or not.
Smoked wood techniques have existed in Jepara Regency since long ago. They were adopted from traditional Javanese stoves, which were usually utilized to smoke fish or corn. As these methods have been applied for a hundred years, many advantages and disadvantages of the method have since been determined.
According to my research, the advantages of the method are: to preserve wood products against termites or other destructive agents; to reach a targeted moisture content (MC) of below 12 percent; to colorize wood products, especially dark or reddish-colored mahogany; and to implement a zero-waste principle. In addition, smoke drying uses cheaper technology than conventional kiln drying, including using wood waste for fuel and not requiring a chamber or hi-tech tools.
The above knowledge has been supported by international journals and other scientific research. As a basic concept, we know that smoke is able to create a chemical substance that covers surfaces, protects against termite attacks and lasts for 5-10 years. Smoke is a captured and condensed form of H2O, which can be linked to other bound and free water (-OH) in the cell walls of dried boards.
But it would not be wise to only mention advantages without drawbacks. The drawbacks of the method include: air pollution produced by burning fuel; high natural defects like staining from high humidity implicated with fungi growth or colorization due to black smog; and the long time required for drying.
I realized that local and indigenous knowledge of smoked wood drying came from the understanding, skills and philosophies developed by Jepara people. The method has its advantages, which have been scientifically proven as beneficial to the furniture industry. However, alleviating the drawbacks and hurdles is still important to producing furniture products that are suitable for export.
Achmad Solikhin is a member of the Indonesian Green Action Forum (IGAF) and a researcher from Bogor Agricultural University, Indonesia.