Kintsugi (golden joint) or kintsukuroi (golden repair) is a Japanese method of restoring broken objects with Japanese lacquer sprinkled with gold or silver powder (gintsugi).
The authentic kintsugi always uses Japanese lacquer (urushi), the sap of the Japanese lacquer tree (Toxicodendron vernicifluum).
Urushi is an organic material which hardens after contact with oxygen and water. If the lacquer is mixed with flour or very fine soil (tonoko) it forms a strong adhesive. Mixed with dyes, we obtain different colors of urushi, including black and red lacquer, known from ancient Japanese art.
The basic kintsugi technique is the maki-e technique, which started in the Edo period.
Maki-e is a Japanese lacquer sprinkled with gold or silver powder to form different decorations. This technique has been used on various objects but is best known for decorations on boxes and recently on fountain pens.
A good kintsugi has a very flat surface. It gives the impression liquid gold is poured into the fracture.
A kintsugi repair begins by repairing the fracture with a urushi-based adhesive, which is home made.
Next comes the patient work of flattening the fracture. All imperfections, large and small, are eliminated by means of a homemade glue, based on urushi, in several stages.
The tiny pores are filled with black urushi.
Finally, a very thin layer of red lacquer is applied, in which gold powder is sprinkled.
This last layer gives the object the beautiful famous golden connection.
After each step, there is a hardening period, from a few days to a few weeks. A repair can therefore take several weeks to several months.