Reported practice · r/Kintsugi

Infilling cracks on a highly textured ceramic surface without sabi putty

How should one build up a crack line for gold work on a ceramic piece whose surface texture makes a conventional sabi-urushi putty impractical, and what role does ro-se-urushi play in that process?

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.

Safety

Ki-urushi and any blend containing it (including ro-se-urushi) are potent skin sensitisers; the reaction is delayed by hours to days, so a lack of immediate irritation does not mean the skin is safe. Direct, repeated contact with the diluted raw lacquer used in the first two crack-tracing passes warrants nitrile gloves and avoidance of bare-skin contact.

What the thread establishes

The answer.

The maker plans to trace the crack in three to four passes: the first two with diluted ki-urushi to wick into microscopic fissures, the remaining one or two with ro-se-urushi to consolidate the seam. Because the extreme surface relief rules out a smooth sabi-urushi coat, the raised line is instead built up with a makiji fill—repeatedly tracing with ro-se-urushi and sprinkling charcoal powder until a smooth, slightly proud ridge is achieved. This ridge then serves as the substrate for the gold. A commenter confirms that ro-se-urushi, a roughly equal blend of roiro-urushi and ki-urushi, sets more quickly and uniformly in narrow voids where air and humidity penetrate poorly, and holds a firmer cure in a somewhat thicker coat than plain ki-urushi. For gaps wider than about 0.1 mm the blend alone is inadequate and a sabi or makiji fill is needed.

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What goes wrongOn porous or unglazed ceramics, masking fluid can leave a permanent stain that is easily mistaken for lacquer seepage. On glassy glazes the fluid adheres poorly and lifts at the edges with minimal disturbance, and tape used to hold parts together during curing can tug the fluid layer off the surface.

What recovers itTest the masking fluid on a hidden area of the specific ceramic before committing to a full seam. If staining has already occurred on a practice piece, the damage is cosmetic; on a finished piece the affected area would need to be sanded back and re-coated.

Wick the crack with diluted raw lacquer

Trace the crack with diluted ki-urushi in two thin passes to draw liquid into microscopic fissures and begin consolidating the seam.

the comment this came from ↗

Consolidate with ro-se-urushi

Apply one or two further passes of ro-se-urushi over the same line to strengthen the infill and close any remaining micro-gaps.

the comment this came from ↗

Build a raised line with makiji

Trace the crack again with ro-se-urushi and immediately sprinkle charcoal powder into the wet trace. Repeat the trace-and-sprinkle cycle until a smooth, slightly proud ridge is formed that will serve as the base for the gold work.

the comment this came from ↗the comment this came from ↗

··Reported

What was reported

Masking fluid removed cleanly from the seams of this particular piece, leaving no mugi-urushi residue on the surface despite the extreme texture, and the maker considers it a successful method for this application. ↗
Masking fluid can permanently stain porous or unglazed ceramics; two commenters independently report staining they initially attributed to lacquer seepage. ↗↗↗
On glassy-glazed surfaces the masking fluid does not adhere well and lifts at the edges easily; tape used to clamp parts during curing can pull the fluid off. ↗
The specific masking fluid used is Holbein latex masking fluid, and the maker stresses that every new surface must be tested before the fluid is applied to the seam. ↗
Ro-se-urushi is a blend of roiro-urushi and ki-urushi, mixed in roughly equal parts for most applications. ↗↗
In narrow fissures where air and humidity penetrate poorly, ro-se-urushi sets more quickly and uniformly than pure ki-urushi, and it holds a firmer cure when applied in a somewhat thicker coat. ↗
For voids wider than approximately 0.1 mm, ro-se-urushi alone is insufficient; a sabi putty or a makiji fill is required. ↗
Makiji is the practice of sprinkling charcoal dust or jinoko powder into a lacquer trace in place of the usual sabi putty, used here because the surface texture makes a smooth sabi coat impractical. ↗↗
The maker considers kintsugi a small subset of the broader urushi craft and notes that many techniques transferable to repair work are not typically taught in kintsugi-specific instruction. ↗

Limits of this source

What the thread does not answer.

No English-language technical reference for kintsugi or broader urushi work was identified; the only book recommended is in Japanese.
The thread does not specify the exact dilution ratio for the ki-urushi used in the first two crack-tracing passes.
How many makiji trace-and-sprinkle cycles are typically needed to reach a smooth raised ridge on a highly textured surface is not stated.

Read the documented methods →