漆Urushi Archive

Method 12

Kintsugi with real urushi

Repair as a lacquer discipline.

Kintsugi is the Japanese practice of repairing broken ceramics with natural lacquer and finishing the repair line with gold, silver, or other metal powders. It sits in the sequence after the vessel has been broken, cleaned, and assessed, and before it returns to daily service. The technique demands patience—multiple cure cycles in a humidity-controlled cabinet over several weeks—precision in filling and leveling to match the original contour, and a clean, dust-free working environment. The result is a repair that is structurally sound, waterproof, and aesthetically celebrated rather than concealed.

Before this: A broken ceramic piece with clean, dry fracture surfaces; all fragments accounted for · Access to a furo (humidity-controlled curing cabinet) or an equivalent stable environment at 70–80 % RH and 20–25 °C · Basic lacquer tools: hake (brush), hera (spatula), masking tape, cutter blade · Understanding that raw urushi is a serious skin sensitiser and that the reaction is delayed by 24–72 hours · A clean, well-ventilated workspace free of dust and drafts

Read the handbook chapter →
Safety gate

This procedure involves direct contact with uncured urushi, which is a potent skin sensitiser with a delayed reaction. Work gloved, keep it off skin, and read the safety chapter before starting. Read Safety First before you begin.
Raw urushi (ki-urushi) is a serious skin sensitiser. Contact can cause a delayed allergic reaction (24–72 hours) presenting as a severe, blistering dermatitis that may spread beyond the contact area. The reaction worsens with repeated exposure. Wear nitrile or neoprene gloves (not latex, which urushi penetrates) when handling any form of raw lacquer. Avoid skin contact entirely; if contact occurs,
Work in a well-ventilated area. While urushi is not significantly volatile at room temperature, dust from clay powders and any solvent thinners (turpentine, kerosene) should not be inhaled.
Dispose of used tissues, brushes, and contaminated materials as chemical waste. Do not allow urushi-contaminated materials to contact food surfaces or skin of others, especially children.
If a severe allergic reaction develops (widespread blistering, swelling, difficulty breathing), seek medical attention immediately and inform the physician that the cause is urushi (Toxicodendron-related urushiol).

Tools

  • hake (lacquer brush)— Flat synthetic brush with high bristle count for sealing; fine neji-gawari or men-sō-hitsu for maki-e lines
  • hera (spatula)— Plastic, metal, or rubber; chosen for elasticity to match vessel curvature; shape may be modified to fit the piece
  • masking tape— Protects surrounding glaze from lacquer stains during filling and sealing
  • cutter blade— Held flat to shave excess filler; used to test smoothness by sliding over the surface
  • film sandpaper (1500 and 2000 grit)— For flattening and smoothing between coats; tsubaki-loaded variant for glaze-sensitive work
  • Tokusa stick— Branch with silica grains; soaked 20–30 min in water or used dry; preferred over sandpaper near glaze
  • ke-bō (hair stick)— Loaded with metal powder for sprinkling over the wet lacquer line
  • cotton swab— For applying small, controlled amounts of lacquer to thin areas
  • tissue (folded)— For wiping back excess lacquer in fuki-urushi technique and absorbing water from clay mixes
  • furo (curing cabinet)— Humidity-controlled cabinet for all urushi cure cycles
  • finger cots— Protective for handling raw lacquer; also used on the pinky to prevent fingerprints from attracting powder

Materials

  • ki-urushi (raw unrefined lacquer)— Primary binder for clay fillers and initial sealing; the most sensitising form of urushi
  • mugi-urushi (lacquer and wheat-flour adhesive)— Used for bonding fractures and sealing porous filler; must be viscous enough to resist pulling
  • kuro-urushi (black lacquer)— Middle coats (naka-nuri); can be thinned with suki-urushi or, in one workshop, with turpentine
  • tonoko (fine polishing-clay powder)— Mixed with water and ki-urushi to form the primary filler paste
  • jinoko (fired-clay powder)— Coarser clay for deeper fills; applied before tonoko
  • kokuso (wood-dust filler)— Fiber added to the clay-lacquer mix for body; keep the amount small to avoid brittleness
  • shi-urushi (white lacquer)— Neutral base coat beneath metal powder to prevent red undertone showing through
  • suki-urushi (transparent lacquer)— Used to thin shi-urushi or kuro-urushi for workable viscosity
  • e-urushi (painting lacquer with bengara)— Stiff, red-tinted lacquer for drawing the kintsugi line before powder application
  • marufun (coarser round metal powder)— Gold, silver, or platinum; 3-gou grade for platinum; No. 1 for gold
  • keshifun (finest gold powder)— Optional finer powder for a smoother, more luminous finish
  • kikumo (polishing compound)— Final buffing agent for a high-gloss metal surface
  • tsubaki (plant fiber)— Loaded onto sandpaper for gentle abrasion that protects glaze
  • masking fluid (watercolor)— Alternative to tape for protecting adjacent surfaces during seam filling

The working sequence

9 steps, each traceable.

Each illustration is a frame taken from the source video at the moment cited, and checked against the step it accompanies. Where no frame passed that check, the step runs without one rather than carrying a misleading picture.

A method merged from several workshops is not a settled standard. 1 of the 8 workshops listed is not cited by any step. 5 further questions the sources leave unanswered are set out at the end.

01 Source · 1:35
No verified frame Open the source at the cited moment.

Clean, assess, and mask the substrate

Wash the broken ceramic thoroughly with clean water to remove all oils, salts, and dust; residual contaminants will prevent lacquer from bonding and cause the repair to fail. Dry the surfaces completely. Assess the fracture: identify which pieces are missing, how deep the gaps are, and whether the glaze is intact around the break. Mask the area immediately surrounding the repair with masking tape, ensuring the tape does not cover any thin glaze losses or hairline cracks that also need sealing. If the piece is a thin-walled vessel (approximately 2 mm porcelain), note that cloth reinforcement is not appropriate and all filling must be done with lacquer-based pastes. Work in a dust-free environment; any particulate that lands on wet lacquer will be embedded permanently.

When it is rightThe fracture surfaces are clean, dry, and free of visible residue. The tape border is sharp and sits just outside the repair zone, leaving all damaged glaze exposed.

When it goes wrongIf oils or salts remain, the lacquer will not adhere and the bond will fail within weeks. Recovery: re-wash with a mild detergent, rinse, dry completely, and re-mask before proceeding.

Workshops differ
  • One workshop uses watercolor masking fluid instead of tape for long seams, applying it close to the line but not into it, then peeling the dried film after filling to leave a clean edge.
Asian Lacquer Craft Exchange Research Project at 1:35 ↗chimahaga at 2:02 ↗
02 Source · 0:42
No verified frame Open the source at the cited moment.

Bond the fracture with mugi-urushi

Prepare mugi-urushi by mixing ki-urushi with wheat flour until the paste is highly viscous—thick enough that it can be pulled up with slight resistance when lifted with a spatula. Apply this mixture to both fracture surfaces using a cotton swab or the flat of a hera, pressing it into the break to ensure full contact. For large missing fragments, first apply a strip of adhesive tape to the interior of the vessel as a backing, making sure the tape does not touch the sticky lacquer surface. Reassemble the pieces, press them together firmly, and secure the joint with wider paper tape or masking tape to hold alignment. Allow the bond to cure in the furo for one to two weeks, or longer if time permits, to achieve maximum strength. Do not disturb the joint during this period.

When it is rightAfter curing, the bond is solid; the pieces do not shift under gentle pressure, and the tape holds them firmly in alignment. The lacquer feels hard under the nail and does not stick to a finger.

When it goes wrongIf the mugi-urushi is too thin or watery, it will not provide sufficient adhesion and the joint will separate. Recovery: remove the tape, re-apply a thicker, more viscous mix, and re-cure. If the bond has already failed, clean the surfaces and start again.

Workshops differ
  • For thin porcelain (≈2 mm), one workshop avoids cloth reinforcement entirely and relies solely on mugi-urushi for both bonding and filling.
  • Another workshop uses ki-urushi mixed with fine ceramic powder (no wheat flour) for the bonding layer, adjusting consistency by adding more powder if the mix is too liquid.
成盐漆作 Lacquer ChengYan at 0:42 ↗Kintsugi by Dmitry Bykov at 5:34 ↗
03 Source · 5:11
No verified frame Open the source at the cited moment.

Fill gaps and missing areas with clay-lacquer paste

Prepare the filler by mixing tonoko (fine clay) with a small amount of water to a smooth paste; if too wet, press with tissue to absorb excess moisture. Add a slightly smaller amount of ki-urushi and mix thoroughly with a hera, scraping all lacquer from the tool to avoid waste. For deeper fills, add a small quantity of kokuso fiber until the surface shows slight texture but is not fluffy. For very deep losses, apply a coarser jinoko mix first, then the finer tonoko mix on top. Wrap the prepared paste in plastic to prevent drying and to release air bubbles. Apply the filler into the gap in small increments over multiple passes: the first pass roughly shapes the form, and subsequent passes use a scalpel or hera to fill bit by bit until the surface is level with the surrounding ceramic. Build the filler slightly above the surface to account for shrinkage. Scrape flat after each application. If the hera cannot follow the vessel's curvature, switch to a more elastic spatula (plastic or rubber). Cure in the furo for two to three days per coat. Repeat the fill-and-cure cycle until the gap is fully built up—this may take three to four passes per side over several weeks.

When it is rightThe filled area is solid, slightly proud of the surface, and follows the vessel's curvature. The texture is smooth and uniform, with no voids or air pockets visible.

When it goes wrongApplying too much at once leads to uneven surfaces and cracking during cure. If the mix is too fluffy (excess fiber), it becomes brittle and will crumble. Recovery: remove the failed layer, re-mix with less fiber or more clay, and rebuild in thinner passes.

Workshops differ
  • One workshop uses mugi-urushi (wheat-flour lacquer) as the primary filler for thin porcelain rather than clay-lacquer paste, filling in small amounts with a scalpel over multiple sessions.
  • Another workshop mixes fine ceramic powder with ki-urushi without water, adjusting to a semi-thick consistency, and applies with fingers for small chips.
  • One workshop notes the clay-water mix dries at room temperature within one day due to water content, whereas the furo-based approach uses 2–3 days per coat.
chimahaga at 5:11 ↗Asian Lacquer Craft Exchange Research Project at 2:51 ↗成盐漆作 Lacquer ChengYan at 1:39 ↗
04 Source · 10:12
No verified frame Open the source at the cited moment.

Trim, level, and abrade the filler

Once the filler is fully cured and hard, remove the masking tape. Hold a cutter blade flat against the surface and shave off excess filler in thin, controlled passes, working from the high points toward the surrounding ceramic. The goal is for the blade to slide over the surface without catching or digging into the substrate. Check by touch with eyes closed: the transition from filler to original ceramic should be imperceptible. For areas near glaze where sandpaper risks damage, use a Tokusa stick—soak it in water for 20 to 30 minutes to soften the branch, then abrade the surface while occasionally re-moistening. You should feel the silica grains under your fingers to gauge pressure. Alternatively, use sandpaper loaded with tsubaki (plant fiber) for a gentler abrasion. After all trimming and abrasion, wipe away all dust with a clean cloth; any residual particulate will create a weak bond for the next layer. If the surface is concave or a step remains, reapply a thin layer of filler and repeat the trim-and-abrade cycle.

When it is rightThe repair surface is flush and smooth; the cutter blade or Tokusa stick slides without resistance, and the transition to the original ceramic is invisible to touch. The surface is free of dust.

When it goes wrongInsufficient trimming leaves a visible ridge or step, compromising the vessel's balance and the final finish. If the blade catches, there is still excess material. Recovery: continue trimming in thinner passes. If the surface is concave, reapply filler and re-cure before trimming again.

Workshops differ
  • One workshop prefers the Tokusa stick over sandpaper specifically to protect delicate ceramic glaze, moistening the stick during work.
  • Another workshop uses 1500 then 2000 grit film sandpaper for flattening between coats, and a rotary cutter for trimming dried clay to match the vessel's curve.
  • A third workshop uses tsubaki-loaded sandpaper for abrasion, noting it roughens pressed areas to improve adhesion for the next layer.
chimahaga at 10:12 ↗Kintsugi Art at 0:28 ↗成盐漆作 Lacquer ChengYan at 3:02 ↗
05 Source · 12:03
No verified frame Open the source at the cited moment.

Seal the filler with lacquer

Re-mask the surrounding area to protect the glaze. Apply a thin coat of mugi-urushi or ki-urushi directly to the filler surface using a flat synthetic hake or a cotton swab for small areas. Allow the lacquer to seep into the porous clay-lacquer layer for five to ten minutes. Then wipe off the excess with a folded tissue, pressing gently until no color transfers to the tissue—this is the fuki-urushi (wipe-on wipe-back) technique. If small pits remain after wiping, fill them with kuro-urushi due to its thickness, which holds in small depressions. For larger surface areas, a flat synthetic brush with high bristle count and good elasticity is preferred; use a thinner brush to finish edges. If the lacquer is too viscous to flow into pores, thin it with a small amount of suki-urushi. Cure in the furo for two to three days until the surface is hard and non-tacky. Test by pressing a finger: it should not stick.

When it is rightThe surface is sealed, smooth, and non-tacky. No sticky residue remains. The lacquer has penetrated the filler pores, creating a unified, waterproof surface.

When it goes wrongIf the lacquer is not wiped back properly, it leaves a glossy, uneven film that will not accept subsequent coats evenly. If the lacquer stains the surrounding glaze, the masking was inadequate. Recovery: remove the glossy film with a solvent wipe (turpentine) and re-apply with proper masking and wiping.

Workshops differ
  • One workshop uses ki-urushi with the fuki-urushi technique for sealing, then fills remaining pits with kuro-urushi.
  • Another workshop applies mugi-urushi directly from the tube, waits 5–10 minutes, then wipes with tissue until no color transfers.
  • A third workshop uses kuro-urushi for sealing seams, noting it can be thinned with turpentine or kerosene if too viscous, and applies inside-out to avoid cross-contamination.
chimahaga at 12:03 ↗成盐漆作 Lacquer ChengYan at 3:59 ↗Kintsugi by Dmitry Bykov at 3:36 ↗
06 Source · 15:09
No verified frame Open the source at the cited moment.

Apply middle coats (naka-nuri) of kuro-urushi

Apply a thin, even coat of kuro-urushi over the sealed filler using a flat hake, working from the center of the repair outward. Avoid running the lacquer onto the surrounding glaze; if it does, it can be cleaned or polished off later on ceramic. If the coat is too thick and runs, thin it slightly with suki-urushi. For vessels with both interior and exterior repairs, work the interior first, then the exterior, to prevent dirtying the inside when handling the outside. Cure in the furo for two to three days. After curing, sand with 1500 grit film sandpaper to flatten, then 2000 grit to smooth. Wipe away all dust. Repeat the coat-and-sand cycle until the surface is uniformly black and smooth, and the underlying filler layer is no longer visible. This may require two or more coats.

When it is rightThe surface is uniformly black, smooth, and level with the surrounding ceramic. No texture of the underlying filler is visible. The sanding marks are fine and even.

When it goes wrongIf the filler layer is still visible after a coat, the lacquer was too thin or the sanding was insufficient. Recovery: apply another coat of kuro-urushi, cure, and sand again. If the surface is uneven, the initial filling was inadequate; return to the filling step.

Workshops differ
  • One workshop emphasizes the inside-out order for teapots to avoid cross-contamination, using a thin brush for internal seams and a flat brush for external surfaces.
  • Another workshop repeats the kuro-urushi coat and 1500/2000 grit sanding cycle until the filler is no longer visible, with each cycle taking 2–3 days in the furo.
chimahaga at 15:09 ↗Kintsugi by Dmitry Bykov at 6:22 ↗
07 Source · 21:35
No verified frame Open the source at the cited moment.

Apply the final base coat for metal powder

Prepare the base coat by mixing shi-urushi (white lacquer) with a small amount of suki-urushi to reduce viscosity to a thin, workable consistency. Apply a thin, even coat over the black lacquer using a flat hake. This neutral beige base prevents the red of bengara (iron-oxide pigment) in the underlying lacquer from showing through the metal powder. Cure in the furo for two to three days. Alternatively, for a traditional gold kintsugi line, draw the repair line with stiff e-urushi (painting lacquer containing bengara) using a fine neji-gawari or men-sō-hitsu maki-e brush. Load the brush and pull the tip continuously to form a line while the left hand rotates the vessel. A slightly over-wide line is acceptable because powder will cover it, but an under-width line exposes the black or brown surface beside the gold. Prioritise complete crack coverage over extreme thinness. Work the interior first if both sides require repair, as it is more difficult; the exterior offers more room to support the hand. After drawing, clean the brush immediately with a non-drying oil (rapeseed or salad oil) to prevent the urushi from hardening in the bristles.

When it is rightThe surface is a uniform, even beige tone (for shi-urushi base) or a continuous, thin red-tinted line (for e-urushi) fully covering the crack with no gaps showing the underlying surface. The line is smooth and unbroken.

When it goes wrongIf the shi-urushi coat is too thick, it may run and pool. If the e-urushi line is narrower than the crack, the brown sabi or black lacquer will show beside the gold. Recovery: for a run, wipe and re-apply thinner; for a narrow line, draw a second pass slightly wider before powder application.

Workshops differ
  • One workshop uses shi-urushi mixed with suki-urushi as a neutral base for platinum powder, preventing red undertone.
  • Another workshop draws the line with stiff e-urushi (bengara-tinted) and notes that judging the semi-dry timing is difficult; the recommended approach is to sprinkle powder immediately after drawing.
chimahaga at 21:35 ↗Asai Yasuhiro at 0:49 ↗
08 Source · 5:48
No verified frame Open the source at the cited moment.

Sprinkle metal powder (maki-e)

Immediately after the base coat or lacquer line is applied (or once it has reached the correct tack), load a ke-bō (hair stick) with marufun—No. 1 gold marufun for gold, or 3-gou platinum marufun for a silver finish. Sprinkle a slightly generous amount over the wet lacquer, holding the ke-bō above the surface so the bristles do not directly stroke the wet line. Apply enough powder that the surface is fully covered, then remove excess by gently tapping or blowing. If a thick lacquer line absorbs the powder, wait about five minutes and check whether the red lacquer has resurfaced; if so, add a second layer of powder. For platinum, apply multiple layers ensuring the edges are well-covered; the powder will appear gray initially but will polish to a silver sheen. Work in a still, dust-free environment. Wear a finger cot on the working hand's pinky to prevent fingerprints from attracting stray powder. Do not touch the wet line with bare fingers.

When it is rightA sharp, continuous line or area of metal powder with no visible red lacquer, brown sabi, or black surface showing through or beside the powder. The powder is evenly distributed and adheres to the tacky lacquer.

When it goes wrongWith too little powder, the ke-bō bristles stroke the wet lacquer and stretch the line. If red lacquer resurfaces through sunken powder after five minutes, the first layer was insufficient. Recovery: add a second layer of powder and allow it to set before proceeding.

Workshops differ
  • One workshop uses No. 1 gold marufun as the primary powder, with round silver powder and keshifun mentioned as alternatives for different finishes.
  • Another workshop uses 3-gou platinum marufun over a shi-urushi base, applying multiple layers for full coverage.
Asai Yasuhiro at 5:48 ↗chimahaga at 23:41 ↗
09 Source · 26:30
No verified frame Open the source at the cited moment.

Fix the powder and polish to finish

Apply a thin coat of high-quality mugi-urushi over the metal powder to lock it in place. Wipe off the excess with a tissue until no color transfers, leaving only a thin film that penetrates the powder. Cure in the furo for over a week to ensure the fixing lacquer is fully hardened. After curing, sand the surface gently with 1500 grit then 2000 grit film sandpaper to remove any surface irregularities and reveal the full luster of the metal. Wipe away all dust. Finally, apply kikumo (polishing compound) to a soft cloth and buff the surface in small circular motions until a high gloss is achieved. The powder should appear bright, durable, and free of scratches. For a matte finish (as in one workshop's soy-sauce purple lacquer variant), sand to the desired texture and skip the kikumo buffing. Allow the finished piece to rest for an additional period before returning it to service.

When it is rightThe surface is a bright, durable metal finish with a high gloss (or controlled matte, per the chosen aesthetic) and no visible scratches. The repair line is sharp, continuous, and structurally sound. The vessel is waterproof and ready for use.

When it goes wrongIf the surface is dull after buffing, the kikumo was insufficient or the sanding was too coarse. Recovery: continue buffing with kikumo in longer passes. If the powder has flaked, the fixing coat was too thin or cure time was insufficient; re-apply mugi-urushi, cure longer, and re-polish.

Workshops differ
  • One workshop finishes with a custom soy-sauce purple lacquer (mixed from purple sugar, cinnabar red, and warm white) sanded to a matte texture, rather than metal powder.
  • Another workshop uses kikumo buffing to achieve a bright silver gloss on platinum marufun.
chimahaga at 26:30 ↗成盐漆作 Lacquer ChengYan at 3:59 ↗

After this stage

After the final polish, the piece should rest in a stable, dust-free environment for at least one to two weeks before returning to active use. The urushi continues to cross-link and harden over time; the repair reaches full strength gradually. Avoid extreme temperature changes, prolonged soaking in water, or abrasive cleaning during this period. For daily use, wash with a soft cloth and mild detergent; do not use steel wool or harsh solvents. Store the vessel in a location away from direct sunlight and heat sources. Periodically inspect the repair line for any signs of lifting or wear, and re-apply a thin coat of urushi if necessary.

Terminology

金継ぎkintsugi
lacquer repair finished in gold; the practice of mending broken ceramics with urushi and metal powder
生漆ki-urushi
raw unrefined lacquer; the primary binder and the most sensitising form
麦漆mugi-urushi
lacquer mixed with wheat flour; used as a structural adhesive and sealer
黒漆kuro-urushi
black lacquer; used for middle coats and filling small pits
透漆suki-urushi
transparent lacquer; used to thin other lacquers for workable viscosity
砥の粉tonoko
fine polishing-clay powder; mixed with water and lacquer to form filler paste
地の粉jinoko
fired-clay powder for the ground; coarser than tonoko, used for deeper fills
刻苧kokuso
wood-dust or fiber filler added to clay-lacquer mix for body
錆sabi
tonoko-and-lacquer putty ground; the clay-lacquer filler layer
拭き漆fuki-urushi
wipe-on wipe-back lacquer technique; apply then wipe excess to seal pores
中塗naka-nuri
middle coats; the intermediate lacquer layers between filler and final finish
蒔絵maki-e
sprinkled metal-powder decoration; the powder application stage of kintsugi
丸粉marufun
coarser round metal powder (gold, silver, or platinum) for maki-e
消粉keshifun
the finest gold powder; used for a smoother, more luminous finish
風呂furo
the humidity-controlled curing cabinet where urushi hardens
刷毛hake
lacquer brush; flat synthetic for sealing, fine maki-e brush for lines
箆hera
spatula; used for mixing and applying filler
研ぎtogi
flattening by abrasion between coats
磨きmigaki
final polishing to achieve the desired surface finish
髹漆kyūshitsu
the discipline of lacquer coating; the broader craft encompassing kintsugi
Full glossary →

Left open

What the sources do not settle.

These are limits of the source material rather than steps omitted. No cited workshop resolves them, so the method above stops where the evidence does instead of filling the gap with something plausible.

  • The exact humidity and temperature range for the furo is not specified in any source; practitioners cite 70–80 % RH and 20–25 °C as standard, but no source in this set gives explicit figures.
  • The total cure time for a complete kintsugi repair varies widely across sources (one to two weeks for bonding up to a month for full refinement); the optimal schedule for a given piece depends on thickness, climate, and number of coats, but no source provides a definitive timeline.
  • One workshop thins lacquer with turpentine or kerosene, while others use suki-urushi; the long-term compatibility of solvent-thinned urushi with subsequent coats is not addressed in any source.
  • The appropriate grade of marufun for different ceramic surfaces (glazed vs. unglazed, thin vs. thick) is not systematically covered; sources mention 3-gou platinum and No. 1 gold without a general selection guide.
  • The role of nori-urushi (rice-paste lacquer) in kintsugi is not demonstrated in any source; it appears only in the context of nunokise (cloth reinforcement), which is explicitly avoided for thin porcelain.