Roiro-nuri: Polishing Urushi to a Mirror Finish

Roiro-shiage (呂色仕上げ), also called roiro-nuri, is the finishing of a hardened urushi top coat by controlled abrasion, extremely thin rubbed lacquer, and final hand polishing. The gloss is made after brushing. This separates it from nuritate, where the last brushed coat hardens as the finished surface. Roiro is often black, but it is a finishing method rather than a colour. (Japan Kogei Association; Japan-Insights)

The process does more than buff a top coat. First, the maker cuts the cured surface flat. Finer abrasion removes that scratch pattern. A wiped film of raw lacquer fills what remains, then cures. Repeating that correction cycle produces a surface fine enough for an ultrafine powder and the palm or fingertips to bring up a sharp reflection.

Separate the material from the method

Japan-Insights makes another useful distinction. Black lacquer made by the iron-reaction method is called roiro-urushi or kuro-roiro-urushi and can be polished to high gloss. Black lacquer made by mixing soot into translucent lacquer does not necessarily behave the same way. Buy by intended use and supplier specification, not by the English word "black." (The Magic of Urushi Lacquer, pp. 9 and 14)

What roiro requires before polishing

A mirror finish enlarges every defect. A dull surface can hide shallow waves and crossed scratches; roiro makes them legible. Start only when the coating below is stable, thick enough to level, and hard enough to produce clean abrasive residue rather than gum, smear, or roll.

• A finished ground and middle build. Roiro cannot correct movement, dents, open pores, or an uneven naka-nuri system.
• An oil-free upper coat intended for polishing. Confirm the lacquer with the supplier. A glossy oil-added nuritate lacquer belongs to a different finish route.
• A complete cure at every depth. A firm skin over softer lacquer will deform under pressure. Use the mechanical checks in Chapter 21.
• Enough film over edges and high spots. Sharp rims, facets, corners, and pen-thread shoulders cut through first. Decide which edges will be protected or polished with reduced pressure.
• A shaped test piece. Prove the charcoal, paper, compound, raw lacquer, oil, and final powder on the same lacquer stack before touching the object.

Tools and materials

• A fully cured upper coat made with a lacquer suitable for roiro polishing
• Soft finishing charcoal such as Suruga charcoal, or one complete documented wet-abrasive system
• Small shaped blocks and pads that support the abrasive without rounding the surface
• Clean water, separate rinse containers, and low-lint cloths for each compound
• Tonoko and rapeseed oil for traditional dozuri, or the matched correction compound used by the method being followed
• Filtered high-quality raw lacquer for suri-urushi, plus cotton, soft cloth, or washi for wiping
• Migakiko, roiro powder, tsunoko, or the specified ultrafine final abrasive
• A clean, monitored furo, strong raking light, magnification, gloves, and powder controls

The traditional finishing cycle

1. Confirm the upper coat is ready. Inspect under raking light and test an inconspicuous area. The abrasive should cut cleanly. If it clogs, drags, or rolls the film, stop and return the piece to controlled cure.
2. Level with soft charcoal and water. Keep the charcoal face dressed to the form and the surface wet enough to carry waste away. Work broad areas evenly, then treat edges and tight curves with less pressure.
3. Reach a uniform matte surface. Remaining glossy islands are low spots. Do not chase them indefinitely if doing so threatens the colour coat or base. Deep lows require another lacquer coat and cure, not more aggressive polishing.
4. Clean and inspect. Remove every particle before changing abrasive. Under raking light, look for charcoal scratches, pits, ripples, edge thinning, and colour change caused by cutting into a lower layer.
5. Carry out dozuri. Work a fine abrasive with oil on cloth to remove the charcoal pattern. Japan-Insights specifies rapeseed oil and tonoko. The Wajima account describes an oil-based polishing powder.
6. Remove oil and abrasive completely. Use the cleaning method specified by the lacquer system. Residue left before suri-urushi can cause beading, uneven wetting, or weak adhesion.
7. Apply suri-urushi. Rub a minute amount of filtered raw lacquer over the polished surface, then wipe it away thoroughly. The goal is to fill microscopic scratches. Pooled lacquer creates a new uneven coat.
8. Cure, then reassess. Put the wiped surface into the furo. After it is mechanically ready, inspect again. Repeat the fine-polish and suri-urushi cycle until the scratch pattern has disappeared to the standard required by the object.
9. Bring up the gloss. Use the specified ultrafine powder with the smallest useful amount of oil. Work with controlled pressure using a clean pad, gloved fingertip, or palm as the tested method requires.
10. Clean and allow a final cure. Remove oil and powder without scratching the surface. A sharp reflection does not prove that the newest lacquer is fully cured, so allow the completed piece a conservative final rest before normal handling.

This sequence follows the shared structure described by the Japan Kogei Association, Japan-Insights, and the Wajima artisan account. Workshops repeat and subdivide the stages differently. The constant is the order of work: flatten first, remove the flattening scratches, refill what remains with an extremely thin lacquer film, cure, and only then attempt the final gloss.

How published methods differ

The paper sequence is a documented teaching method, not a conversion chart for charcoal. Likewise, a pen can be rotated and inspected from every angle while a bowl, panel, or carved form needs different supports and pressure. Copy the logic of a method before copying its numbers.

Judge readiness without a timetable

Separate surface set from mechanical readiness. A set film may tolerate a gloved touch and still be too soft to level. A coat ready for roiro should resist printing, cut into clean residue, and retain its shape under the pressure used by the chosen abrasive. If the abrasive loads immediately or the surface develops a greasy smear, stop.

Kojima Yuri demonstrates a breath response as an additional check during a rubbed-lacquer sequence. Tamenuri Studio uses longer rests for some pen finishing stages. Neither practice creates a universal number of hours. Temperature, relative humidity, airflow, lacquer grade, water content, and film thickness all matter. Record them as described in Curing and troubleshooting.

Reading common faults

Watch levelling, rubbed lacquer, and final polishing

The sequence is easier to understand on video because pressure, slurry, scratch removal, and the amount wiped away are difficult to infer from a still image.

The archive's timestamped roiro method joins the three-part Kojima Yuri sequence with the Tamenuri Studio material notes, still frames, correct-result checks, and recovery guidance.

Continue from here

• Grades and types explains raw, transparent, coloured, and black finishing lacquers.
• Abrasives covers papers, charcoal, powders, blocks, and contamination control.
• Uwa-nuri and nuritate explains the upper coat and the unpolished alternative.
• Tamenuri shows how roiro polishing is applied to a translucent colour build.
• Sanding and polishing places roiro inside the full progression from the base to the final surface.
• Togidashi maki-e uses controlled polishing to reveal a buried design flush with the ground.
• Defect diagnosis covers clouding, soft cure, contamination, dust, and wrinkling outside the polishing stage.