Reported practice · r/Urushi
A practitioner is planning a kinmushikui-nuri (金虫喰塗) kawari-nuri finish in which gold leaf is set into a textured surface of cured lacquer, and asks for critique of a ten-step plan and clarification of what the Japanese sheath-maker meant by 'clear' urushi.
This page is written from one discussion thread. It records what practitioners reported and what they linked it to — not documented workshop practice. Every claim below links to the comment it rests on, so you can read it in context.
Raw urushi (ki-urushi) is a potent skin sensitiser; contact can trigger a delayed urushiol-type dermatitis that may appear 12–72 hours after exposure. Wear nitrile or latex gloves, long sleeves, and avoid any skin contact with the lacquer, turpentine thinners, or the cured-but-still-tacky surface. The risk is cumulative: repeated light exposures build sensitivity over time.
What the thread establishes
The 'clear' urushi the sheath-maker referred to is kijiro-urushi (木地呂漆), a transparent lacquer that is not colourless but lets the substrate show through. The overall procedure is workable as a beginner-friendly kawari-nuri: build a base of roiro-urushi, press in organic hulls to create a relief, remove the hulls to leave voids, then fill those voids with gold leaf over kijiro-urushi and seal with further transparent coats. The critical practical points are keeping every coat thin and even (especially after the hulls are removed, when lacquer migrates into the depressions), and curing at a controlled, gradually rising humidity so the thicker layers dry slowly enough to avoid wrinkling.
What goes wrongIf a coat of urushi is applied too thickly, it pools into the depressions left by the removed hulls and pulls away from the raised areas. The pooled lacquer in the voids then fails to cure properly and wrinkles (chijimi, 縮み), trapping uncured urushi underneath. This is a particular risk with the thicker coats used in this technique, in contrast to the exceedingly thin layers of fuki-urushi where wrinkling is not a concern.
Wet-sand the wooden piece to at least 800 grit to give the first lacquer coats a sound, even surface.
Apply three to four coats of roiro-urushi (呂色漆) thinned at roughly 3 parts lacquer to 1 part turpentine. Allow each coat to cure fully before sanding lightly and applying the next. This base is the layer that will ultimately hold the gold leaf.
While the final roiro coat is still wet, press spent barley hulls, rice hulls, or a mixture of both into the surface. Let the piece cure fully so the hulls are locked in the lacquer.
Strip all hull material from the cured surface, taking care that no fragments remain. What is left is a field of small voids in the cured lacquer.
Apply a thin coat of kijiro-urushi (木地呂漆, the transparent lacquer) over the textured surface and immediately press gold leaf into the voids. Allow to cure fully.
Rub the surface gently by hand to lift loose leaf, being careful not to dislodge leaf seated in the voids. Follow with a light wet-sand at high grit.
Re-apply kijiro-urushi and gold leaf to any voids that have become exposed after sanding. Cure, then repeat the rub-and-sand cycle until all voids are filled.
Once the surface is smooth and all leaf is secured, apply four to six further coats of kijiro-urushi, sanding lightly between coats, to build up a protective transparent seal over the gold.
Cure each layer at a slightly lower humidity first (around 70–75 %), then raise to about 80 % after half a day to a day. This slow, staged cure reduces the risk of wrinkling in the thicker coats and keeps the transparent lacquer paler so the gold shows through more clearly.
Limits of this source