1. What happens when lacquer hardens?
The sap collected from the lacquer tree is used as a paint. This paint does not harden because water or solvents evaporate. Instead, its main component, urushiol, combines with oxygen in the air and links molecules together to harden, helped by an enzyme called laccase. [6]
Enzymes act like catalysts that help chemical reactions happen. For laccase to work well, it needs moisture. Therefore, items coated with lacquer are placed in a humid room called a "muro," not in a dry room. [6]
According to materials from Tottori Prefecture, the guideline is about 25°C (77°F) and 70–80% humidity. Materials from the Tokyo National Research Institute for Cultural Properties suggest 20–30°C (68–86°F) and 75–80% relative humidity, showing a range depending on the source. [6][6]
With normal lacquer liquid, if the temperature is low and humidity is low, the reaction becomes slow. So, lacquer is a paint that hardens by "moistening and reacting," not by "drying." But when this paint is applied to wood, why do artisans wipe it off? [6]
2. Why wipe off the lacquer you just applied?
"Wiped lacquer" (fuki-urushi) is a process where raw lacquer is rubbed into wood and then wiped off thoroughly with paper or cloth. [6] Raw lacquer means lacquer collected from the tree, filtered to remove wood chips and other impurities. [6]
The wiping is done to make the wood grain stand out. Because it does not cover the wood thickly, the wood grain remains visible. Repeating this process several times to dozens of times creates a shine. The number of repetitions depends on the type of wood and the desired finish. [6]
After each application, the item is hardened in the humid room described earlier before the next layer is rubbed in. In Okayama Prefecture, Soubara lacquerware features items where raw lacquer is applied to the wood body, polished, and dried repeatedly to highlight shine and grain. [6]
Materials from the Kagawa Lacquer Art Research Institute also describe a process of rubbing raw lacquer into the base and hardening it to create a waterproof film. Thin layers of lacquer also serve to protect the wood. [6]
With so many layers applied, how much lacquer can actually be collected from one tree? [6]
3. How little lacquer comes from one tree?
When a cut (called "abe") is made in the trunk of a lacquer tree with a plane, milky white sap oozes out. Scraping this up is called lacquer tapping, which continues from mid-June to around October. Even then, only about 180–200g of lacquer can be collected from one tree. [6]
200g weighs about as much as one small paper carton drink. The technique of applying thin layers repeatedly, like in wiped lacquer, is a way to spread this precious lacquer across the wood. [6]
In Japan, imported lacquer makes up most of what is sold. In the Forestry Agency’s White Paper on Forests and Forestry, domestic production was 1.8 tons out of 37.7 tons consumed in 2018, which is about 5%. [6] Ministry of Agriculture, Forestry and Fisheries materials state that depending on the year and survey method, domestic lacquer is introduced as approximately 9%. [6]
Repairs to cultural properties are driving up demand for domestic lacquer. According to the Agency for Cultural Affairs policy, from fiscal year 2018, domestic lacquer is used in principle for preservation repairs of National Treasures and Important Cultural Properties buildings. It is predicted that an average of about 2.2 tons of domestic lacquer will be needed per year. [6]
If you divide 2.2 tons by 200g per tree, a simple calculation gives about 11,000 trees. This is a rough estimate using the maximum yield per tree and does not show the actual number of trees used. [6]
People have used this labor-intensive material for a long time. When did they start? [6]
4. How did people use lacquer in the past?
According to materials from the Kagawa Lacquer Art Research Institute, the history of lacquer in Japan goes back 9,000 years. Containers coated with lacquer have been found at Jomon period sites. [6]
The Kakinoshima Site in Hakodate City, Hokkaido, was registered as a World Heritage site in 2021 as part of the "Jomon Prehistoric Sites in Northern Japan." It is said to have produced lacquer decorations from an early stage of the Jomon period and is sometimes introduced as "among the oldest in the world." [6]
It is too early to say definitively that it is "the oldest," but it is currently described as "among the oldest." What is certain is that people seem to have used lacquer for everyday tools since the Jomon period. The shine of wiped lacquer comes at the end of this long relationship. However, whether the name and technique of wiped lacquer itself has continued since the Jomon period is a separate issue. [6]
5. How can you see lacquer's shine and wood grain on bowls and chopsticks?
If you have wooden bowls or chopsticks at home, hold them up to window light at an angle. Compare whether the wood grain shows through and if the shine looks soft and lustrous. Items with wiped lacquer should show the wood pattern more clearly than those with thick coatings. [6]
Checking if labels or boxes say "lacquer" is also a clue. It can be difficult to judge if something is lacquer just by looking at the surface. [6]
For safety, do not touch raw lacquer. The component urushiol causes rashes when touched, but it is said that hardened products do not cause this worry. However, items that have not fully hardened may cause skin irritation if touched. [6]
Domestic lacquer and cultural property repairs are explained with numbers in the Ministry of Agriculture, Forestry and Fisheries’ "aff" November 2022 special issue and the Forestry Agency’s White Paper on Forests and Forestry. Reading these next might change how you see lacquer. [6]