Transparent Urushi — Instructions for Use

There are no standard answers in lacquer work. What follows is only a reference process — adjust it, add or drop steps to suit your own habits.

 

1. Materials

Materials

• Transparent urushi

• Fine filter cloth (the most demanding item on this list) or filter paper — how well you filter decides whether you end up with specks and halo rings

• Silver leaf / silver powder (or 80–90 grit aluminium flake powder as a substitute)

• Adhesive Urushi for Gold Powder (the undercoat for laying leaf)

• Polishing powder: tonoko (or fine pumice), wheat flour…

• A little oil (plant oils such as rapeseed, soybean or peanut oil) — used only for the final polishing

• Lint-free cotton pads

Tools

• One good lacquer brush (flat, soft, holds a clean edge) + one cheap "spreading" brush

• Sandpaper: 1000 / 2000 / 3000 grit, plus 2000-grit foam-backed paper (conforms to curves, prevents burn-through); add 5000 / 7000 if you want to go finer

• Charcoal sticks (low cutting force, levels flatter)

• Brush-cleaning tools and solvent

Environment

• A drying cabinet: 20–25 °C, 70–80% RH — for normal curing

• A low-humidity space: about 50–60% RH at room temperature — used specifically for "setting" transparent urushi. Most people skip this step

• Dust-free, out of direct sun, no draughts

 

2. Safety (do not skip)

Uncured urushi causes allergic contact dermatitis, and most people will eventually react after repeated contact. The first contact may be fine — sensitisation builds up. This is the number one reason beginners give up.

• Wear nitrile gloves and long sleeves throughout; lacquer can pass through thin gloves, so change them often

• Work ventilated; no eating, drinking or smoking in the work area

• Lacquer on skin: wipe it off with oil first, then wash with soap and water (water alone spreads it further)

• If a rash appears: stop immediately, wash, treat it, and see a doctor if it is severe. Do not push through it

 

3. One iron rule (counter-intuitive, but you must remember it)

Everyone says "urushi needs humidity to cure" — true.

But with transparent urushi:

Going into high humidity too early = a dark, stuffy surface with no clarity.

The correct order: first let it "set" in low humidity, then move it into the drying cabinet to cure.

Those who skip this step always end up complaining that "the transparent coat went black."

Two habits to build, in order of importance: ① filter properly ② dry slowly at low humidity first.

 

4. Standard process: silver-leaf overcoating (follow this; every other overcoat job is a variation of it)

Lay the silver leaf → overcoat with transparent urushi ×3–4 → wipe-on finishing and polishing

Step 1 · Lay the silver leaf

1. Brush Adhesive Urushi for Gold Powder where the leaf will go.

2. Wait for the "tacky but not sticking" moment: press lightly with your little finger — a slight grip, but no lacquer pulling up onto the finger, means it is time ✅

• Sticky, lacquer pulls up → too early (the leaf will tear)

• No tackiness at all → too late (the leaf will not stick)

3. After laying the leaf, press it down firmly — anywhere that is not pressed flat becomes a hidden problem when you sand later.

Every adhesive urushi has a different "tacky but not sticking" window. Pick one and use it long-term until you know its temperament.

Step 2 · Apply the transparent coat

1. Stir it thoroughly before use — the lacquer separates: the top layer is oil-rich (slow to dry, or never dries), the bottom is strongly drying. Never take from the surface layer alone.

2. Filter the transparent urushi (you will coat several times, so filter a larger batch).

3. The brush must be thoroughly washed and dried — overcoating demands extreme cleanliness.

4. Spread it out with the cheap brush, then even it out with the good brush — one pass horizontally, one pass vertically.

5. ⚠️ It must be even: uneven thickness dries to uneven color, light and dark.

6. Never let lacquer pool at edges or in texture.

Step 3 · Drying (this is where it most often goes wrong)

Stage	Conditions	Time (starting point)
① Set	Low humidity 50–70%, 20–25 °C, away from light	6–12 hours, until the film has basically formed
② Cure	Drying cabinet, 70–80% RH, 20–25 °C	12–24 hours to hard dry; light sanding is then possible
Alternative	Slow drying at low humidity throughout	The clearest result, but the longest

 

These are reference values only — adjust to your local climate.

Do not put it in the sun and do not add heat; cold, slow drying is perfectly fine.

Step 4 · Sanding and leveling (preventing burn-through is the priority)

Pass	Tool	Purpose
1st	2000-grit foam-backed paper	The foam conforms to curves and silver leaf, preventing burn-through
2nd	1000-grit paper	Once you know the surface, you can cut faster
3rd	Charcoal	Low cutting force, hard to burn through, levels flatter
4th	2000 grit	Refine
Final	3000 grit (5000/7000 if you want)	Remove scratches, preparing the surface for polishing

 

Stop as soon as the whole surface is uniformly matte. Leveling comes from many thin coats plus gentle, step-by-step sanding — never try to get there in one pass. Do not over-sand the silver-leaf areas.

Step 5 · How many coats

3–4.

• Fewer coats → clearer, but not enough material to level, and not enough of that subtle depth

• More coats → softer and more veiled, but transparency drops

Step 6 · wipe-on finishing and polishing (the "polished" look comes from this step)

1. wipe-on finishing: with a lint-free cotton pad, wipe on an ultra-thin coat of Wipe-Build Semi-Clear Urushi, then wipe almost all of it off — leave only "the breath" of lacquer, not a film.

2. Dry for about 1 day.

3. Polishing: tonoko powder plus one drop of oil on a cotton pad, work in circles until you can see your reflection, then buff clean with dry cotton.

4. Repeat "wipe-on → dry → polish" at least 3 times. Gloss is built by repetition, not by one long session.

Step 7 · Wait for "the color to open"

After the piece is finished, the hiding power of the transparent urushi weakens with time and what lies underneath becomes clearer and clearer ("the color opening"). Two to three hours in the sun can speed this up. This is a characteristic, not a defect — allow for the change from the very start.

 

5. Over wood grain (wipe-on technique)

• Wiping beats brushing: small amounts applied many times give better control of thickness and color, and are far less likely to wrinkle or go too dark.

• Keep everything dry-sanded at the start: only after every face has been wiped or brushed 3 or more times and the lacquer has fully sealed the wood pores may you begin wet sanding — wetting the wood too early deforms it.

• Fill the grain or not, depending on the material: tight material with fine grain can be left unfilled; coarse material with large grain must be filled first (mix an epoxy/emulsion filler with titanium white to make a filling paste, spread it thin and even; as it shrinks on drying, top it up 1–2 times, then dry-sand at 2000).

• Rosewood-type woods are mostly finished with natural transparent urushi; pale woods are mostly finished with synthetic clear lacquer.

 

6. Numbers quick reference (for reference only)

Item	Value
Leafing window	"Tacky but not sticking": a slight grip, no transfer
Number of transparent overcoats (silver flake)	3–4
Set (low humidity)	about 6–12 hours @ 50–70% RH
Cure (drying cabinet)	about 12–24 hours @ 70–80% RH, 20–25 °C
Sanding ladder	2000 foam → 1000 → charcoal → 2000 → 3000
wipe-on finishing, drying	about 1 day
wipe-on + polish cycles	3 or more
Speeding up "the color opening"	2–3 hours in the sun