By the 6th century, the processing of urushi had reached a high level of artistry in Asia. The raw material for the lacquer is extracted from the resin of the East Asian lacquer tree (Rhus vernicifera, 漆の木, Urushi no Ki), which is related to the vinegar tree. The raw varnish is initially cloudy, but turns clear after curing through polymerization, becoming very light to dark amber.
Traditionally, urushi is often pigmented red (with iron oxide and cinnabar) or black (with soot), but can also be processed as semi-transparent urushi.
Sometimes other material is embedded in urushi, e.g. gold or silver dust or leaf metal (蒔絵, Makie), mother-of-pearl (螺鈿, Raden or 青貝, Aogai) or eggshells (卵殻, Rankaku).
For the refinement of the cracks I use different pigments:
Powder gold Rosenoble with 23.75 carat fine gold content, white gold or powder silver.
Brass, bronze or copper powder.