Chapter 22

Sanding and Polishing Urushi: From Flatness to Gloss

There is no single abrasive ladder from bare wood to finished urushi. Sanding wood, levelling a ground coat, cutting brush marks from cured lacquer, refining scratches, revealing decoration, and producing a mirror gloss are different jobs. Each removes a different amount of material and has a different stopping point. Choose the job and the intended finish before choosing a grit.

The mistake to avoid is treating every abrasive as a finer version of the last one. A soft charcoal block behaves differently from waterproof paper. Tonoko mixed with oil does different work from migakiko. Micro-Mesh uses its own grade numbers. A sequence is reliable only when its materials, support, lubricant, lacquer, cure state, and inspection method stay together.

Abrasion can expose uncured lacquerA surface may feel dry while a lower layer remains soft. Wear clean nitrile gloves, keep wet slurry and used abrasives off your skin, and treat a breakthrough as contact with uncured urushi. Fine powders should stay out of the air. Do not blow residue from the object; use the controls in Chapter 11.

Start with the job, not the grit

Job	What the abrasive must do	Evidence that the stage is complete
Prepare bare wood	Remove tool marks, torn grain, glue, and handling damage while preserving the intended form	The surface is clean and consistent under raking light; no scratch remains deeper than the chosen final preparation
Level ground or middle coats	Cut high spots and ridges so the next coat lands on a true surface	The surface is evenly matte, without isolated glossy low spots that can be reached safely
Key a cured coat	Remove dust nibs or provide the texture required by the next step without changing the shape	The defect is gone and the film remains continuous over edges and high points
Refine scratches	Replace the previous scratch pattern with a shallower, uniform one	Inspection under clean raking light shows no marks from the earlier abrasive
Develop gloss	Remove or fill microscopic scratches with fine compound, rubbed lacquer, and final powder	The clean, oil-free surface reflects evenly and retains that gloss after residue is removed
Reveal decoration	Remove a covering layer until metal, shell, colour, or pattern appears at the intended plane	The design is exposed evenly without cutting into the decorative material or surrounding ground

Abrasives remove high spots; they do not fill low spotsIf glossy pits remain while the surrounding lacquer grows thin, stop. Another coat is the correction. Finer paper will polish the high areas but will not make a low area rise to meet them.

Grit numbers are not a common language

Read the complete label. FEPA uses a P prefix for coated abrasives and defines each grade as a particle-size distribution, not a single diameter. ANSI and JIS use other scales. Micro-Mesh uses a separate numbering system; its own guidance places Micro-Mesh 1500 near the scratch range of conventional wet-or-dry 400. The identical number on two products can therefore describe very different cuts. (FEPA; Micro-Surface)

Marking or material	How to read it
P800, P1500, P2500	FEPA grades for coated abrasives. Keep the P when recording the schedule.
800, 1500, 2000 without a prefix	The number is incomplete unless the maker or source identifies the standard and product.
Micro-Mesh 1500 to 12000	A proprietary scale. Do not insert these numbers into a sandpaper progression as though they were FEPA or JIS grades.
Charcoal, whetstone, tokusa	Natural or manufactured abrasives whose cut depends on material, preparation, wear, and pressure. Test the actual piece.
Tonoko, dozuri powder, migakiko, tsunoko	Loose powders and compounds used for different refinement stages. Colour and name alone do not establish particle size.

Record the brand, product line, grading system, lubricant, backing, and wear state. "#1500" by itself is not enough information to reproduce a result.

Choose the endpoint before abrasion

Finish	Normal endpoint	What not to do
Fuki-urushi	Wood grain remains visible with a matte to satin wiped film; sanding between coats is used only when raised fibre or defects require it	Do not build a mirror-polishing schedule onto a finish whose character comes from the wood
Nuritate	The last coat hardens as brushed and is left unpolished	Do not sand the successful final coat; correction means curing, levelling, and applying another final coat
Tamenuri	A translucent build whose lighter and darker areas depend partly on film thickness and shape	Do not sand edges until they become bright by accident; this is a breakthrough, not the intended pooling effect
Roiro	A level upper coat followed by charcoal or a documented paper sequence, dozuri, rubbed lacquer, and final powder	Do not begin final compound while deeper levelling scratches remain
Togidashi, raden, and metal powder	A planned reveal at a specific layer or plane	Do not borrow an ordinary black-lacquer progression without accounting for the hardness and height of the decoration

Prepare before touching the surface

Prove mechanical readiness. Test an inconspicuous area or a matched sample. Hard lacquer cuts cleanly; soft lacquer loads the abrasive, smears, rolls, or takes a fingerprint.
Map the vulnerable areas. Rims, corners, ridges, pen-thread shoulders, raised decoration, and the crests of brush marks have less material above them.
Support the abrasive. Use a flat block on planes and a shaped pad on curves. Bare fingertips create hollows and round crisp transitions.
Separate materials. Give each abrasive or compound its own cloth, water, pad, and storage. One coarse grain can put a visible line through a nearly finished surface.
Set the light before starting. Use raking light from at least two directions and magnification for high-gloss work. Touch alone cannot distinguish a deep scratch from a clean fine pattern.
Plan cleanup. Know how the complete method removes water, oil, slurry, and compound before the next coat. Do not improvise solvent use on the finished object.

A working method that transfers between systems

Start with the least aggressive abrasive that will do the job. If it cannot remove the target defect in a controlled time, step back once. Repeated heavy pressure with a fine abrasive often rounds the surface before it removes the defect.
Dress the block or pad to the form. Keep a flat block flat. Shape charcoal and pads for concave or convex areas so contact is broad rather than concentrated at one point.
Use the lubricant specified by the method. Water carries lacquer waste during wet levelling. Oil belongs to particular polishing stages. Switching them changes the cut and may contaminate the next coat.
Work a controlled pattern. Straight passes and a ninety-degree change of direction make the scratch pattern easier to read on broad surfaces. On cylinders, rotate the object methodically rather than polishing the visible side more heavily.
Clean before inspecting. Slurry can fill scratches and create a false impression of smoothness. Remove it with the method's clean cloth and view the bare surface under raking light.
Remove the whole previous pattern. Do not advance because the surface feels smoother. The new, finer pattern must replace every mark left by the earlier abrasive.
Use fresh material. A worn sheet may stop cutting and begin burnishing. A loaded sheet can drag debris across the lacquer. Replace it before compensating with pressure.
Treat edges last and lightly. The broad areas consume most of the work. Edges need fewer passes and a supported contact that does not roll over them.
Stop when the evidence changes. Colour shift, exposed cloth or wood, a sudden dark line, or soft material in the slurry means the abrasive has reached a different layer. Clean, inspect, and decide whether the finish needs rebuilding.

Published progressions and their limits

Source and finish	Published progression	What the numbers mean there
Fine Woodworking, fuki-urushi	Prepare bare wood to 320 if sanding is needed; light 320 between wiped coats; four to five coats with long cures	A practical wood finish that retains grain, not preparation for a polished lacquer film
Tamenuri Studio, fuki-urushi	Final wood preparation from about #400 to #1200 depending on the wood and desired colour; later abrasion changes with the coat and finish	Smoother wood absorbs less lacquer and may darken less, so the starting surface is part of the colour design
Japan-Insights, traditional lacquer build	Lower and middle coats harden, then are abraded with charcoal and water; the hardened upper coat receives soft charcoal before dozuri	The abrasive changes with the layer and purpose. No universal paper equivalent is supplied.
Kojima Yuri, teaching sequence	Wet #600 to #800 on a block for pre-coat flatness; a separate final sequence uses #1000, #1200, #1500, #2000, and #3000 before compound and rubbed lacquer	Two different jobs inside one workshop method. The earlier pair prepares for another coat; the later series prepares for mirror polishing.
Tamenuri Studio, coloured pen build	Pigmented kijiro layers are refined through about #2500, with the last colour layer checked around #5000; translucent coats receive only gentle high-grit correction	The exact grades belong to a pen schedule designed to preserve colour and avoid cutting through thin translucent layers.

These accounts disagree only if the finish and stage are omitted. A #320 wood surface, #800 pre-coat surface, and #3000 roiro surface solve different problems. Keep the source's substrate, lacquer, cure, and endpoint attached to its numbers. (Fine Woodworking; Tamenuri Studio; Japan-Insights)

Read the slurry and scratch pattern

Observation	What it usually means	Response
The abrasive loads immediately or leaves a greasy smear	The lacquer is too soft, the paper is clogged, or oil entered a water stage	Stop. Clean a test area and verify cure before resuming with fresh material.
Small glossy islands remain in a matte field	They are low spots below the abrasive plane	Estimate the film remaining on nearby high spots. Recoat rather than chase deep lows.
One directional scratch survives two finer stages	The earlier pattern was never fully removed, or a coarse particle contaminated a later stage	Return to the finest abrasive that removes it reliably, then repeat the progression with clean tools.
A bright or differently coloured line appears on an edge	The abrasive has entered the layer below	Stop widening it. Decide whether the intended design allows the reveal; otherwise rebuild the coating.
The surface looks glossy while wet but dull when clean	Water or oil is filling the scratches temporarily	Judge only after cleaning and drying. Continue the correct refinement stage rather than adding more oil.
Fresh random hairlines appear during final polish	Contaminated powder, cloth seams, dirty gloves, hard skin, or point pressure	Replace and separate the materials, then return to the finest stage that removes the damage.
The reflection is sharp in one area and distorted in another	The surface has different local curvature or was levelled unevenly	Inspect the shape, not only the gloss. A polishing compound cannot correct a wave that requires levelling or recoating.

Edges, curves, holes, and texture

Edges and rims. Mask them during broad levelling when the design allows, then finish them with fewer supported passes. Never wrap paper around an edge and pull back and forth.
Cylinders. Divide the circumference into repeatable sections or rotate on a suitable support. Uneven hand pressure quickly makes a pen or handle oval.
Concave areas. Shape a soft pad or charcoal face to match. A hard block contacts only the edges of the hollow.
Holes and threads. Keep slurry out of functional fits. Abrasive residue and film loss can change dimensions even when the visible finish looks correct.
Textured lacquer. Do not flatten the texture by default. A soft cloth, horsehair bundle, or technique-specific powder may polish raised and recessed areas without erasing the pattern.
Shell and metal powder. Their hardness differs from the surrounding lacquer. Follow the decorative method's reveal sequence and inspect frequently under magnification.

Watch the materials and the scratch progression

Abrasive materials, 16:55. Tamenuri Studio surveys papers, charcoal, whetstones, powders, and their different roles in urushi work. Watch on YouTube.

Progressive wet abrasion, 15:10. Kojima Yuri demonstrates supported levelling, direction changes, edge caution, and the progression from #1000 through #3000. Watch on YouTube.

For the rubbed-lacquer and final-powder stages that follow this preparation, use the archive's timestamped roiro method and Chapter 20.

Continue from here

Abrasives covers the tool kit, blocks, papers, charcoal, and polishing powders.
Wood preparation deals with grain, moisture, pores, and shaping before the first lacquer coat.
Naka-nuri explains why flat middle coats matter before the upper coat.
Roiro-nuri covers dozuri, suri-urushi, tsuya-age, and final mirror polishing in full.
Curing gives the readiness tests to use before any abrasive touches lacquer.
Togidashi maki-e and raden introduce technique-specific bury-and-reveal work.
Defect diagnosis covers clouding, soft cure, contamination, dust, and wrinkles that sanding alone cannot repair.

Sources for this chapter