Asian lacquer

by Kenta Takeshige

Asian lacquer is a sap obtained from lacquer trees. Lacquer trees can be roughly classified into three types. The main components of these sap are also different. Lacquer tree species are widely spread from Southeast Asia to East Asia. It is said that Asian lacquer causes rash. When these sap adheres to human skin, it may cause an allergic reaction.

• Rhus verniciflua (Toxicodendron vernicifluum)
  Common name: Lacquer Tree
  This tree species naturally occurs in China, Korea, and Japan. The sap of this tree contains the resin urushiol, which takes in oxygen from the air and chemically polymerizes and hardens. Recent field surveys have increased the likelihood that this species is also growing in Bhutan.

• Rhus succedanea (Toxicodendron succedaneum)
  Common name: Vietnamese Lacquer Tree
  This tree species naturally occurs in Cambodia and Vietnam, and was planted in Taiwan from Vietnam. The main component of sap is laccol. The varieties of this tree species grow in Bhutan, China, Korea, and Japan as well, and are called Wax Tree because of a source of candle-making.

• Gluta usitata (Melanorrhoea usitata)
  Common name: Burmese Varnish Tree
  This tree species grows naturally in Myanmar and Thailand. The main component of sap is thitsiol.

Urushi lacquer in Japan

10 to 15 years after planting a lacquer tree (Urushi no Ki), one can start collecting sap. Lacquer (Urushi) harvest is from May to October. The amount of sap that can be collected from a single lacquer tree is about 200 grams. The collected sap is filtered to remove impurities. This raw lacquer is called Ki-Urushi. After that, further purification can be done. By stirring the liquid of Ki-Urushi, the particles are made finer (Nayashi) while making the ingredients uniform, and heat is applied to gradually remove the water (Kurome). Lacquer refined in this way is called Kijiro-Urushi, or Suki-Urushi which means transparent lacquer. Colored lacquer can be made by mixing pigments with Kijiro-Urushi or transparent lacquer such as Shuai-Urushi.

※ Generally, when it is called Suki-Urushi, it often refers to lacquer mixed with oil.

Since constant temperature (20 to 25°C) and humidity (75% to 85%) are required to create an environment where Urushi lacquer can harden, lacquer work is dried in a room where the temperature and humidity are measured and under control. Unlike other paints, Urushi lacquer does not dissolve in any solvent. Once Urushi lacquer hardens, it exhibits excellent resistance to water, heat, alcohol, solvents, acids, alkali and mold.