Lacquer trees maintain a certain amount of sap internally and excrete it to protect itself when its bark is breached, which is referred to as ‘lacquer sap’.
To collect lacquer sap, the bark of living trees is removed, exposing the sap secreting organ, which is breached to encourage the sap to ooze out. Raw lacquer sap contains various substances such as urushiol, nitrogen, gum, water, etc. The ash colored milky sap has a bittersweet taste and oxidizes into a brown color. Prolonged oxidization hardens the surface into a dark brown colored cover that prevents further oxidization, which is why lacquer sap is described as having ‘hardening’ and ‘drying’ characteristics.
-from. 'Chapter 1. About Ottchil'

Lacquer sap is hand-collected from early June to late October from standing trees. The trees should be at least six years old; the best age for harvest is between eight to ten years. While Jichil(arborization: cutting off branches and collecting lacquer from them) and Hwachil(collecting lacquer by heating lacquer tree) techniques were mainly used in the past, ‘collecting lacquer and cutting off’, ‘collecting and curing’, ‘collecting from upper and below parts at the same time’ methods are the main collecting techniques used today.
-from. 'Chapter 2. Tools and Material for Lacquering'

Wood is the most frequently used material for lacquer work. To prevent warping and cracking during the lacquering process, the wood base must be tough, hard and wellseasoned. Here are three examples of wood base treatment: Jeopchil(lacquering by rubbing-in), Ottchil-oligi(overcoating) and Moksimjeopi(hemp-cloth covering).
-from. 'Chapter 3. ‘Applying Lacquer

Pottery in the early time was fragile and inconvenient, mainly due to lower firing temperature and its water-absorbing property. Lacquer was one of the finest ways to complement those weaknesses. Lacquer makes earthenware solid and water-repelling. Nowadays, pottery and porcelain are lacquered mainly for widening the aesthetical expression, accordingly the technique and material to unite both extraordinary expression tools are diversifying.