Copperplate Engraving 铜版画

The Honeybee, Plate VII·40s·Lemo-Opuscarby Lemomo

An intaglio plate that engraves itself: a burin cuts swelling lines into copper, a proof is pulled, and the figure builds up — outline, hatching, cross-hatching — until engraved lettering, magnified details and a hand-laid wash make a finished plate.

The demo: A natural-history plate engraves itself: the burin cuts the copper, the bee builds up line by line, and a watercolour wash brings it to life.

Museum labelsScience explainersBrand heritage

Style prompt · STYLE.md

An intaglio plate that engraves itself: a burin cuts swelling lines into copper, a proof is pulled, and the figure builds up — outline, hatching, cross-hatching — until engraved lettering, magnified details and a hand-laid wash make a finished plate. References (grammar only): 19th-century natural-history plates — Haeckel, Audubon, Westwood, the Britannica copperplates (centred subject, numbered roundels, roman title over an italic name, "del." / "sculp." credits, the plate mark); Hogarth and Doré for the burin line (hatching that follows the form, crossing only in half-tones); hand-coloured plates for washes laid after printing. Never copy a plate, pose, border or title.

1. Essence, and what it is not

An intaglio print: the line is ink held in a groove a burin cut into copper. Three rules:

Tone is made of lines, never of fills. Light is bare paper; half-tone is one family of parallel lines; shadow a second family crossing it; the deepest dark a third, lozenge-making family. No grey fill anywhere in the ink.
Every line swells and tapers. The burin enters fine, bites deeper mid-run and lifts out to a point. Lines thicken where the form turns from the light and vanish where it faces it; contours are cut in several runs and thin where runs hand over. A uniform-width line reads as a pen or vector drawing — never.
Colour comes afterwards, by hand: transparent watercolour laid flat region by region over the finished black print, spilling past the lines, pooling at its edges, ink always on top. A film may stay monochrome long; colour arriving is an event.

Not a woodcut (black block, white gouges — woodcut), not a pen sketch (loose broken lines — urban-sketch), not an engineering drawing (blueprint), not a sepia filter.

2. Materials & rendering

The sheet is the world: 1920×1080 world units of laid paper (cream, ~#f1e8d2) with world-space texture (fibres, laid lines, sparse foxing) that zooms with the camera; a pressed, bevelled plate mark and a ruled border (rule + hairline) frame it.
Ink is one warm near-black (~#1c1510). Width ratios: outlines heaviest (swelling ×0.45–1.35), first hatching from a hair (~0.18 px) to ~2 px, crossing ~0.8×, third family ~0.6×, hair and stipple finest. Spacing is relative to the figure (~1/180 of its height, a little wider per later family) so small figures never go grey.
Swell law for every hatch line: width × (0.2 + 0.8·sin(πu)^0.7), tapered over its first and last ~22 %. Families switch on by tone thresholds (~0.14, ~0.5, ~0.75 on a 0–1 tone).
One light direction for the whole film (upper left by convention); heavier outlines away from it; tone fields come from the shape (pillow lighting, analytic spheres and cylinders), never from texture. Occlusion is geometric: lines stop at the shapes in front.
Roundels: double-ruled circle, ruled-machine ground with a white halo round the subject, content authored at a large radius and scaled in. Leaders: hairlines from a dot on the part to the rim, routed with clearance, a small italic figure number at the root.
Hand colouring multiplies over paper and under ink: a few px of spill, slight misregister, tide-line at the wet edge, low-frequency density lift, occasional backruns, granulation; each region blooms from where the brush touched.
Copper (when shown): polished warm metal, polishing hairlines, a soft reflected window; grooves = dark trough + bright burr toward the light. The burin (lozenge steel shaft, bevelled face, mushroom handle) is held low and turned ≤ 15° off the line so the fresh groove shows; swarf is a narrowing ribbon curling ahead of the point, one edge lit.

3. Colour logic

The print is two values, paper and ink; all tone is line density.
Colour is transparent wash only, in muted earth and mineral pigments, one stronger pigment at most. Never opaque, never on lettering, rules or paper outside the figure.
Reserve it: the whole subject at one moment, or only the part that matters — or none.
Example wash sets: an amber insect with blue-grey wings; a map with a sea-green coastal band on buff land; one madder-rose organ on an otherwise black anatomy plate.

4. Type & subtitles

Lettering belongs to the plate: roman capitals (Bodoni Moda; title ~44–56 px, wide tracking; labels ~15–19 px), italics for scientific names (~20–24 px), script (Pinyon Script) for notes, fixed size, balanced over two lines, never shrunk.
Roman letters are cut glyph by glyph; script is written in one left-to-right stroke. Nothing fades in.
Subtitles: script on a deckled paper slip, bottom centre, ≤ 2 lines, never over a label. Hold ≥ max(1.8 s, speech + 0.6 s). An engraved note stays in frame chars ÷ 12 + 1 s from when it starts writing.

5. Motion quality

Cutting order is the animation: outline → first hatching sweeping across each form → crossing → darks, hair, stipple. Strokes run at constant burin speed, many at once (a few for outlines, dozens for hatching).
A long single stroke may be followed by the camera; start it partly cut so no frame is empty. Keep a full build to a few seconds.
Roundels fly on an eased arc with a small lift, growing log-linearly to size. Colour blooms from one point with a ragged front and a wet rim that dries; regions staggered.
Nothing fades or slides like UI: lines are cut, text cut or written, colour blooms, sheets are pressed, peeled or laid down.

6. Camera grammar

The camera is a loupe over a sheet. A vocabulary, not a route. Opening and ending come from the topic.

Move	Expresses	Can serve
Loupe following the burin tip	One point of attention; making	a first mark; a signature
Log-zoom pull-out	The line was part of something larger	scale reveal; context
Push to a part, ride with its roundel	Where → what, in one take	an invisible detail; a mechanism
Tilt/pan along the sheet at reading zoom	Labels in order	a parts list; a coastline
Pull back while something flies	Everything placed in relation	acceleration; summary
Locked frame, or a ≤ 2 % breathing push	The plate as document	reading time; colour moving
Raking view across the copper	The groove as depth	the cost of craft
Cut from mirrored copper to true proof	Reversal	a hidden truth; before/after

Framing: subject inside the plate mark, labels and roundels in the margins; order details so push-ins never crop a note early. Transitions from printmaking only (proof pulled, tissue guard laid over, region burnished out and re-cut, new sheet on the bed); no dissolves or wipes.

7. Sound palette

Foley by material: paper (peel crackle, slip tapped down, tissue rustle, sheet whoosh); press (roller rumble, thump); copper and steel (high band-passed burin hiss with chatter and faint plate ring, swarf pings, a tick on lift, circular scribe, burnishing rub); ink and water (pen scratch, ticks for cut letters, a water plip and wet brush swish). Hatching = micro-scratches denser each pass.
Room: a quiet workroom (faint clock), paper room once the print exists.
Instruments (choose): harpsichord, string quartet, solo cello or viola da gamba, lute, chamber organ, glass harmonica for a cold subject. Plucked and dry while lines are cut; bowed or sustained only when something soft arrives; tiny tings for a scribed ring, a low pluck on landing.
Silence is real: cut room tone too, keep at most one small sound.
Mix: melody an octave above the voice, music ~half under speech, −14 LUFS. Voice: a quiet curator or naturalist.

8. Native moves

A menu: use the ones your story needs.

The cut. Burin mid-stroke, swarf rising, nothing else. Fits: the first line of a treaty; a watchmaker's scribe; a coast being charted.
The three passes. Form gains volume pass by pass. Fits: a building from its plan; a portrait emerging; a skill improving.
Magnification roundel. Ring scribed, burnished, re-cut larger, flown to a margin with a leader, label cut on landing. Fits: a gear in a clock; a pollen grain; a harbour inset on a chart.
The proof. Sheet peels off; mirrored copper becomes true paper. Fits: a secret out; a draft made final; a coin's die and strike.
States of the plate. A region burnished out and re-cut. Fits: a border redrawn; before/after; a design revision.
Hand colouring. Washes bloom after the print. Fits: one organ lit; a flag on a historical map; a ripening fruit.
Natural size. A tiny true-scale figure beside the engraving. Fits: a seed by its tree; a chip by its circuit; a stamp by its enlargement.
The finished plate. Every label and credit, locked. Fits: a museum label; a frontispiece; a certificate.

9. Pitfalls of the medium

Uniform width reads as pen → swell hatches, pinch contours between runs (hatch({swell}), outline({run, pinch})), keep wMin hair-fine.
Overlaps without occlusion → pass occluders as excl (subtracted ring by ring; even-odd would cancel overlaps).
Outline-only parts beside a hatched body → hatch along each part's axis, a dark at every joint.
Burin along the cut hides the groove; big skew looks like poking → ≤ 15°. Regular swarf helix reads as a spring → vary winding, twist, light one edge.
Reflections over grooves wash them out → copper light first. Roundels authored small freeze sub-pixel → author large, scale in. Leaders hugging the subject read as crossing it → clearance.
A long early stroke never draws → the ink's early exit must look ahead by the longest stroke.
A push-in cropping a fresh note breaks the reading rule → put consecutive details on one side.
Scientific names: TTS may manage, ASR won't → give the checker a plain spelling.

10. Engine

demo/engine/: burin.js (B.Ink ordered stroke store + schedule, B.hatch, B.engraveTone, B.contourHatch, B.outline/B.stroke, B.stipple, B.fur, tone fields), plate.js (drawSheet, engraveText, writeScript, roundelFrame), wash.js (Wash), copper.js (copper, burin, swarf), index.js (engraveShape(svgPath, {at, light, spacing, style}): any SVG shape → engraved figure). demo/example/index.html engraves and colours a four-pointed spark in ~20 lines; code and function table in DEMO.md "Engine reference".

11. Variation space

You decide subject, details, order, opening, ending, camera path, colour, pacing and music. Use cases are grammar for the order and duration of information; build your own timeline from the user's facts.

Use case	Information order	Hold per layer	Length
Museum label / case screen	title + scientific name → detail + term + note (×N) → where to see it	title ≥ 2.2 s; note ≥ chars/12 + 1 s; final ≥ 4 s	30–40 s
"One minute on …"	question → name → 2–3 facts → one number → follow prompt	number ≥ 2.5 s alone	35–60 s
Textbook figure	figure → parts labelled one by one → caption	label ≥ chars/12 + 1 s	20–45 s
Craft heritage	object → 2–3 craft details → maker / edition	as above	30–45 s
Map / site plan	place → insets → legend → visiting info	inset ≥ 3 s; legend ≥ 4 s	30–45 s

All far from our demo:

Structures: states of one plate (one view re-cut three times as a place changes); a book of plates (four small plates turned like pages, one fact each, no roundels); a dissection (parts labelled in teaching order, colour only on the part taught).
Openings: the finished proof burnished back to its first line; on paper at 1× (title cut first, figure grows below); raking light over blank copper as the design is traced.
Endings: plate beside its proof; the natural-size figure held alone; a blank new sheet laid on the stack.

Swapping demo/content.json and rebuilding is a technical check that the engine re-flows, not a way to make a film.

How our demo was made (story, shots, score, end card, build, content fields): DEMO.md. Read it after your treatment exists.

# Copperplate Engraving — Style Prompt

> An intaglio plate that engraves itself: a burin cuts swelling lines into copper, a proof is pulled, and the figure builds up — outline, hatching, cross-hatching — until engraved lettering, magnified details and a hand-laid wash make a finished plate.
> References (grammar only): 19th-century natural-history plates — Haeckel, Audubon, Westwood, the *Britannica* copperplates (centred subject, numbered roundels, roman title over an italic name, "del." / "sculp." credits, the plate mark); Hogarth and Doré for the burin line (hatching that follows the form, crossing only in half-tones); hand-coloured plates for washes laid after printing. Never copy a plate, pose, border or title.

## 1. Essence, and what it is not

An **intaglio print**: the line is ink held in a groove a burin cut into copper. Three rules:

1. **Tone is made of lines, never of fills.** Light is bare paper; half-tone is one family of parallel lines; shadow a second family crossing it; the deepest dark a third, lozenge-making family. No grey fill anywhere in the ink.
2. **Every line swells and tapers.** The burin enters fine, bites deeper mid-run and lifts out to a point. Lines thicken where the form turns from the light and vanish where it faces it; contours are cut in several runs and thin where runs hand over. A uniform-width line reads as a pen or vector drawing — never.
3. **Colour comes afterwards, by hand**: transparent watercolour laid flat region by region over the finished black print, spilling past the lines, pooling at its edges, ink always on top. A film may stay monochrome long; colour arriving is an event.

Not a woodcut (black block, white gouges — `woodcut`), not a pen sketch (loose broken lines — `urban-sketch`), not an engineering drawing (`blueprint`), not a sepia filter.

## 2. Materials & rendering

- **The sheet is the world**: 1920×1080 world units of laid paper (cream, ~`#f1e8d2`) with world-space texture (fibres, laid lines, sparse foxing) that zooms with the camera; a pressed, bevelled **plate mark** and a ruled border (rule + hairline) frame it.
- **Ink** is one warm near-black (~`#1c1510`). Width ratios: outlines heaviest (swelling ×0.45–1.35), first hatching from a hair (~0.18 px) to ~2 px, crossing ~0.8×, third family ~0.6×, hair and stipple finest. Spacing is **relative to the figure** (~1/180 of its height, a little wider per later family) so small figures never go grey.
- **Swell law** for every hatch line: width × (0.2 + 0.8·sin(πu)^0.7), tapered over its first and last ~22 %. Families switch on by tone thresholds (~0.14, ~0.5, ~0.75 on a 0–1 tone).
- **One light direction** for the whole film (upper left by convention); heavier outlines away from it; tone fields come from the shape (pillow lighting, analytic spheres and cylinders), never from texture. **Occlusion** is geometric: lines stop at the shapes in front.
- **Roundels**: double-ruled circle, ruled-machine ground with a white halo round the subject, content authored at a large radius and scaled in. **Leaders**: hairlines from a dot on the part to the rim, routed with clearance, a small italic figure number at the root.
- **Hand colouring** multiplies over paper and under ink: a few px of spill, slight misregister, tide-line at the wet edge, low-frequency density lift, occasional backruns, granulation; each region blooms from where the brush touched.
- **Copper** (when shown): polished warm metal, polishing hairlines, a soft reflected window; grooves = dark trough + bright burr toward the light. The **burin** (lozenge steel shaft, bevelled face, mushroom handle) is held low and turned ≤ 15° off the line so the fresh groove shows; **swarf** is a narrowing ribbon curling ahead of the point, one edge lit.

## 3. Colour logic

- The print is two values, paper and ink; all tone is line density.
- Colour is **transparent wash only**, in muted earth and mineral pigments, one stronger pigment at most. Never opaque, never on lettering, rules or paper outside the figure.
- Reserve it: the whole subject at one moment, or only the part that matters — or none.
- Example wash sets: an amber insect with blue-grey wings; a map with a sea-green coastal band on buff land; one madder-rose organ on an otherwise black anatomy plate.

## 4. Type & subtitles

- Lettering belongs to the plate: **roman capitals** (Bodoni Moda; title ~44–56 px, wide tracking; labels ~15–19 px), **italics** for scientific names (~20–24 px), **script** (Pinyon Script) for notes, fixed size, balanced over two lines, never shrunk.
- Roman letters are **cut glyph by glyph**; script is **written** in one left-to-right stroke. Nothing fades in.
- Subtitles: script on a deckled paper slip, bottom centre, ≤ 2 lines, never over a label. Hold ≥ max(1.8 s, speech + 0.6 s). An engraved note stays in frame chars ÷ 12 + 1 s from when it starts writing.

## 5. Motion quality

- **Cutting order is the animation**: outline → first hatching sweeping across each form → crossing → darks, hair, stipple. Strokes run at constant burin speed, many at once (a few for outlines, dozens for hatching).
- A long single stroke may be followed by the camera; start it partly cut so no frame is empty. Keep a full build to a few seconds.
- Roundels fly on an eased arc with a small lift, growing log-linearly to size. Colour blooms from one point with a ragged front and a wet rim that dries; regions staggered.
- Nothing fades or slides like UI: lines are cut, text cut or written, colour blooms, sheets are pressed, peeled or laid down.

## 6. Camera grammar

The camera is a **loupe over a sheet**. A vocabulary, not a route. Opening and ending come from the topic.

| Move | Expresses | Can serve |
|---|---|---|
| Loupe following the burin tip | One point of attention; making | a first mark; a signature |
| Log-zoom pull-out | The line was part of something larger | scale reveal; context |
| Push to a part, ride with its roundel | Where → what, in one take | an invisible detail; a mechanism |
| Tilt/pan along the sheet at reading zoom | Labels in order | a parts list; a coastline |
| Pull back while something flies | Everything placed in relation | acceleration; summary |
| Locked frame, or a ≤ 2 % breathing push | The plate as document | reading time; colour moving |
| Raking view across the copper | The groove as depth | the cost of craft |
| Cut from mirrored copper to true proof | Reversal | a hidden truth; before/after |

## 7. Sound palette

- **Foley by material**: paper (peel crackle, slip tapped down, tissue rustle, sheet whoosh); press (roller rumble, thump); copper and steel (high band-passed burin hiss with chatter and faint plate ring, swarf pings, a tick on lift, circular scribe, burnishing rub); ink and water (pen scratch, ticks for cut letters, a water plip and wet brush swish). Hatching = micro-scratches denser each pass.
- **Room**: a quiet workroom (faint clock), paper room once the print exists.
- **Instruments** (choose): harpsichord, string quartet, solo cello or viola da gamba, lute, chamber organ, glass harmonica for a cold subject. Plucked and dry while lines are cut; bowed or sustained only when something soft arrives; tiny tings for a scribed ring, a low pluck on landing.
- **Silence** is real: cut room tone too, keep at most one small sound.
- **Mix**: melody an octave above the voice, music ~half under speech, −14 LUFS. Voice: a quiet curator or naturalist.

## 8. Native moves

A menu: use the ones your story needs.

- **The cut.** Burin mid-stroke, swarf rising, nothing else. *Fits:* the first line of a treaty; a watchmaker's scribe; a coast being charted.
- **The three passes.** Form gains volume pass by pass. *Fits:* a building from its plan; a portrait emerging; a skill improving.
- **Magnification roundel.** Ring scribed, burnished, re-cut larger, flown to a margin with a leader, label cut on landing. *Fits:* a gear in a clock; a pollen grain; a harbour inset on a chart.
- **The proof.** Sheet peels off; mirrored copper becomes true paper. *Fits:* a secret out; a draft made final; a coin's die and strike.
- **States of the plate.** A region burnished out and re-cut. *Fits:* a border redrawn; before/after; a design revision.
- **Hand colouring.** Washes bloom after the print. *Fits:* one organ lit; a flag on a historical map; a ripening fruit.
- **Natural size.** A tiny true-scale figure beside the engraving. *Fits:* a seed by its tree; a chip by its circuit; a stamp by its enlargement.
- **The finished plate.** Every label and credit, locked. *Fits:* a museum label; a frontispiece; a certificate.

## 9. Pitfalls of the medium

- Uniform width reads as pen → swell hatches, pinch contours between runs (`hatch({swell})`, `outline({run, pinch})`), keep wMin hair-fine.
- Overlaps without occlusion → pass occluders as `excl` (subtracted ring by ring; even-odd would cancel overlaps).
- Outline-only parts beside a hatched body → hatch along each part's axis, a dark at every joint.
- Burin along the cut hides the groove; big skew looks like poking → ≤ 15°. Regular swarf helix reads as a spring → vary winding, twist, light one edge.
- Reflections over grooves wash them out → copper light first. Roundels authored small freeze sub-pixel → author large, scale in. Leaders hugging the subject read as crossing it → clearance.
- A long early stroke never draws → the ink's early exit must look ahead by the longest stroke.
- A push-in cropping a fresh note breaks the reading rule → put consecutive details on one side.
- Scientific names: TTS may manage, ASR won't → give the checker a plain spelling.

## 10. Engine

`demo/engine/`: `burin.js` (`B.Ink` ordered stroke store + `schedule`, `B.hatch`, `B.engraveTone`, `B.contourHatch`, `B.outline`/`B.stroke`, `B.stipple`, `B.fur`, tone fields), `plate.js` (`drawSheet`, `engraveText`, `writeScript`, `roundelFrame`), `wash.js` (`Wash`), `copper.js` (copper, burin, swarf), `index.js` (`engraveShape(svgPath, {at, light, spacing, style})`: any SVG shape → engraved figure). `demo/example/index.html` engraves and colours a four-pointed spark in ~20 lines; code and function table in DEMO.md "Engine reference".

## 11. Variation space

You decide subject, details, order, opening, ending, camera path, colour, pacing and music. Use cases are **grammar for the order and duration of information**; build your own timeline from the user's facts.

| Use case | Information order | Hold per layer | Length |
|---|---|---|---|
| **Museum label / case screen** | title + scientific name → detail + term + note (×N) → where to see it | title ≥ 2.2 s; note ≥ chars/12 + 1 s; final ≥ 4 s | 30–40 s |
| **"One minute on …"** | question → name → 2–3 facts → one number → follow prompt | number ≥ 2.5 s alone | 35–60 s |
| **Textbook figure** | figure → parts labelled one by one → caption | label ≥ chars/12 + 1 s | 20–45 s |
| **Craft heritage** | object → 2–3 craft details → maker / edition | as above | 30–45 s |
| **Map / site plan** | place → insets → legend → visiting info | inset ≥ 3 s; legend ≥ 4 s | 30–45 s |

All far from our demo:

- Structures: **states of one plate** (one view re-cut three times as a place changes); **a book of plates** (four small plates turned like pages, one fact each, no roundels); **a dissection** (parts labelled in teaching order, colour only on the part taught).
- Openings: **the finished proof burnished back** to its first line; **on paper at 1×** (title cut first, figure grows below); **raking light over blank copper** as the design is traced.
- Endings: **plate beside its proof**; **the natural-size figure** held alone; **a blank new sheet** laid on the stack.

Swapping `demo/content.json` and rebuilding is a technical check that the engine re-flows, not a way to make a film.

---

How our demo was made (story, shots, score, end card, build, content fields): [DEMO.md](DEMO.md). Read it after your treatment exists.

Director's notes for the demo film

One example among many. Don't reuse its story, arc, shots, props or timings.

Demo: The Honeybee, Plate VII (40.0 s) · engraving.mp4 · source in demo/ · all words from demo/content.json

Story & structure

A scene demo, not a story: a museum object label for the screen next to a case. One object (the honeybee), its name, three things you did not know about it, and where to see the real one ("see the living hive in Gallery 4").

Structure (40 s): copper ECU → proof pulled → pull out to the plate → three magnified details (eye, hamuli, corbicula), each flying to its slot → silence → hand colouring → locked final plate → tissue-guard end card.

How the native moves served information in this demo:

The cut itself was the hook: the first frame is the burin mid-stroke in copper, curl of copper rising ahead of the point. Nothing else is on screen, so the eye has one place to go.
The build (outline → first hatching → cross-hatching → darks and hair) was the "this is a serious, made thing" beat, kept under 5 s and under the title.
The magnification roundel was the information carrier: a ring is scribed around the part, the inside is burnished clean and re-engraved at magnification, and the roundel flies to its slot trailing a leader line. The viewer sees where the detail is and what it looks like in one move. Its label (roman capitals, italic term, script note) is engraved when it lands.
Hand colouring was the climax, after a real silence and after all information is on the plate, so it read as reward, not as new information.
The final plate was the poster: every label, the call to action and the engravers' credits at once, locked off.

The use-case table as first written for this demo, with the shot structure we had in mind for each (examples, not recipes):

Use	Shot structure
Museum object label (the demo)	copper ECU → proof pulled → pull out to the plate → 1–4 magnified details, each flying to its slot → silence → hand colouring → locked final plate
"One minute on …"	same, with the narrator carrying the notes; end on the plate as the thumbnail
Textbook figure	no copper opening; start on paper at 1×, engrave the figure, then label parts with leaders one by one; no colour or colour only on the part being taught
Craft heritage (a watch, a violin, a knife)	ECU of the burin on the object's contour → build → roundels on the mechanism → colour only the material that matters (gold, varnish)
Map or site plan	engrave the coastline or plan, roundels become insets (a building, a harbour)

Shots

The camera is a loupe over the plate. Beat by beat in the demo:

Beat	Camera	Why
Hook (0–2.5 s)	4.2× on copper, follows the burin tip, 3° roll	one point of attention; the cut is the hook
Proof pulled (2.5–3.2)	locked while the sheet peels across	the medium's own transition
Build (3.2–6.2)	pull out 4× → 1×, log-zoom with screen-linear dolly feel	scale reveal: the curve was a bee's abdomen
Detail 1 (9.4–15.0)	push to 4.3× on the eye; ride with the roundel as it lifts off and flies to its slot, easing out to a 1.45× reading frame	the signature one-take: where → what → label
Detail 2 (15.0–19.4)	tilt down at 1.45× from the upper to the lower left, keeping detail 1's note in frame	faster, same grammar
Detail 3 (19.4–23.75)	pull back to the full plate while the roundel flies, then push in to read (after detail 2's note has had its time)	acceleration; reading time respected
Gather, silence, colour	full plate; a 2 % breathing push during colour	the colour moves, not the camera
Final plate	locked off	the poster

Motion timings in this demo: the first line is one stroke followed by the camera, 5.4 s long, so at frame 0 it is already a third cut; strokes run 6–90 at once; roundels lift 30 px at mid-flight and grow to radius 120; colour regions bloom over 1.25–1.6 s each and start 0.42 s apart.

Score structure

Three layers: room tone (a quiet workroom with a faint clock on copper; paper room after), foley keyed to picture events, and a baroque chamber score.

Score: harpsichord + string quartet, 96 BPM, D major. music/score.py reads events.json: each detail section (A long / B tilt / C pull-back) is written once and placed where the film puts it; the outro shifts with the end of the details, so any number of details gets a matching score. Under narration the melody sits an octave up, out of the voice's band. Engraving sections are all pizzicato (the burin's small precise cuts), density growing pass by pass; each roundel = a high "ting" as the ring is scribed, a rising line as it flies, a low pizz as it lands. Before the colour: a run that stops dead, then true silence (1.25 s). The colour is the first time the strings use the bow. The final plate lands on a V–I cadence.
Silences: 2.0–2.5 s (burin lifted, before the press thump and the downbeat) and 25.0–26.25 s (before the first drop of water).
Foley as built: burin = band-passed hiss (2.6–9 kHz) with chatter clicks and a faint plate resonance (1.18/2.31/3.47 kHz); swarf = tiny 5–9 kHz pings; lift = metallic tick; press = low roller rumble (J-cut 0.35 s early) and a thump; peel = dense paper crackle; hatching = granular micro-scratches whose density rises with each pass; ring = circular scribe; burnish = soft rub; roundel flight = paper whoosh; landing = paper tap; letters = dotted ticks; notes = pen scratch at ~4 Hz strokes; colour = a falling water "plip" then a wet brush swish per region; end card = tissue rustle (J-cut).
Narrator: Kokoro bm_fable (en-gb), speed 0.92, a gentle naturalist; music ducked to ~50 % under him (the bowed strings duck least).

Palette & props

The sheet: 1920×1080 world units, laid paper #f1e8d2, world-space paper texture (fibres, laid lines, sparse foxing #9a6a34). Plate mark (the pressed, bevelled rectangle) at (70, 44)–(1850, 1036): plate tone #e8ddc2 at 55 % inside; bevel dark on the top/left walls, light on bottom/right (light from the upper left). Ruled border: 2.4 px rule + 0.8 px hairline 9 px inside, (100, 72)–(1820, 1008).

Ink: #1c1510. World line widths at 1× zoom: outlines 1.8–2.4 (swelling ×0.45–1.35), first hatching 0.18–2.0, cross-hatching ×0.78, third family ×0.6, hair and stipple 0.6–0.9. Hatch spacing on a 600-px figure: 3.1–3.7 px (first), ×1.1 (cross), ×1.25 (third). Hatch thresholds on a 0–1 tone: first family from 0.14, crossing from 0.46–0.5, third from 0.74–0.78.

Light: {x: −0.55, y: −0.62, z: 0.56}.

Lettering: Bodoni Moda (title 50 px, tracking 0.16; labels 17 px, tracking 0.14), italics for Latin (20–24 px), Pinyon Script for notes (29 px). Subtitles: Pinyon Script 38 px, #2b1e14, on a deckled paper slip (#f4eddb, soft shadow) at the bottom centre, max width 860, up to two lines; on 0.1 s before the line, off 0.6 s after it; never over the call to action.

Roundels: radius 120, double rule (2 px + 0.75 px, 4 px inside), ruled ground of horizontal lines every 11 local units; content drawn for a 500-unit radius and scaled in. Slots in order: upper left (300, 300), lower left (300, 700), lower right (1620, 700), upper right (1620, 300). An unused slot shows the specimen at natural size (plate ≈ 20 cm wide, so a 13 mm bee is 0.19× the main figure).

Leaders: 0.95 px, from a dot on the part to the roundel's rim, routed around wings and body with ≥ 34 px clearance (one waypoint), a small italic figure number near the root.

Hand colouring: abdomen amber #d9962a, thorax ochre #a8743e, head #8a6242, eyes #6e4a3c, wings pale blue-grey #a9c3cf (alpha 0.5), legs #7a5a3c, pollen #eaa21a (alpha 0.95). Multiply over paper; 3.5 px spill, 2/1.5 px misregister, tide-line at the wet edge, low-frequency density lift (0.55), 1–2 backruns in large regions, granulation.

The copper (opening only): base #5e2a12 → #94502c → #4e220e, a swirl of polishing hairlines (overlay), a soft studio window reflected across the plate (four panes, blurred 14 px, over a 90 px room glow), dark room toward the frame edges. Grooves: dark trough #240c05, a bright burr rgba(255,226,186) offset toward the light, a warm glint on the far wall. Burin: lit face #d9e0e6, shadow face #262b30, sharp ridge highlight, brass ferrule, mushroom-shaped wooden handle with grain; turned 0.22 rad (≤ 15°); swarf a thin, narrowing copper ribbon curling irregularly (turns open out as it grows, an occasional twist).

Subjects: the honeybee (subjects/bee.js) with three drawn magnifications — compound eye, hamuli (wing hooks), corbicula (pollen basket) — in subjects/details.js; a second built-in subject, the great scallop (subjects/scallop.js), used by content_alt.json.

End card

The title is part of the plate (engraved, not a separate card). End card: a translucent tissue guard falls over the plate; on it, engraved: film title, style name, LEMO-OPUSCAR, LemoLab × Claude Opus 5.5, three credit lines. The "LemoLab × Claude Opus 5.5" sign-off belongs to this library's demo only; a user's film carries no LemoLab credit and no copy of this card.

Build notes

sh styles/engraving/demo/build.sh              # voice → check → score → events → mix → cue check → srt → frames → mux → stills

demo/engine/: burin.js (lines), plate.js (sheet, lettering, roundels), wash.js (colour), copper.js (copper, burin, swarf), index.js (public entry + engraveShape).
demo/subjects/: bee.js, details.js (eye, hamuli, corbicula roundel drawings), scallop.js (second built-in subject).
demo/film.js: timeline (96 BPM grid), camera, render; reads content.json. demo/mix.py: foley + voice + ducked stems. demo/music/score.py: the score (written by a composer sub-agent against the cue map in demo/TREATMENT.md). demo/tools/cuecheck.py: score accents vs picture events (all within 1 frame) and the silence level.
Render with core/render/video.mjs --workers 2; frames take 60–500 ms (copper and colour frames are the slowest).

Pitfalls tied to this demo's props:

Wing veins must close their cells. Random vein strokes look fake; define long veins as curves and snap cross-veins onto them (bee.js, FX).
Leg joints drawn as full capsules look like beads. Exclude the previous segment so only the distal cap shows.
Two renders of the same demo folder collide: video.mjs writes its segments to <demo>/out/, so render the main and alt films one after the other.
Burin skew: 30° read as poking beside the line; 0.22 rad fixed it.
Leaders hugging a wing read as crossing it until routed with ≥ 34 px clearance.
"Apis mellifera": Kokoro says it acceptably but whisper can't transcribe it; the line uses the asr field.

content.json fields

demo/content.json drives every word, number and colour.

Field	Type	Range	If out of range
`title`	string	≤ 22 characters	longer titles run past the latin line's width; shorten or drop to 44 px in `film.js`
`latin`	string	≤ 30 characters	read time grows (chars/12 + 1 s must fit before the first push at 9.4 s)
`plate_no`, `series`	string	≤ 10 / ≤ 48 characters	series collides with the title above ~48 characters
`subject`	`"bee"` \| `"scallop"`	built-in subjects	unknown → `bee`; a new subject is a module returning `{ink, regions, focus}` with an `ol0` first stroke (see `subjects/scallop.js`)
`details[]`	array of `{name, latin, note, focus}`	1–4	>4 are ignored; fewer leaves slots → the first empty one shows the natural-size figure; the timeline re-flows (first 9 beats, others 7 beats each)
`details[].focus`	string	bee: `eye`, `hamuli`, `corbicula` (drawn magnifications); any subject: its `focus` keys	a key with no drawn magnification gets a live magnification of the figure itself
`details[].note`	string	≤ 60 characters (2 lines at 29 px)	a third line starts to meet the next roundel
`colors[]`	`{region, color}`	regions of the subject (bee: abdomen, thorax, head, eyes, wings, legs, pollen; scallop: shell, bands, ears)	unknown regions are skipped; order = order of colouring
`caption`	string	≤ 50 characters	must stay readable ≥ chars/12 + 1 s inside the 4.4 s final plate
`signature.left/right`	string	short	—
`nat_size_label`	string	≤ 16 characters	—
`voice.voice`, `voice.speed`, `voice.lines[]`	Kokoro voice, 0.8–1.0, `{id, text, asr?}`	ids: `title`, `d1`…`dN`, `close`	a line longer than its section overlaps the next one; keep d-lines ≤ 4.5 s
`end.film_title`, `end.style_name`, `end.credits[]`	strings	credits ≤ 3 lines of ≤ 35 characters	longer lines break the end card's reading time

Steps: edit (or copy) the JSON → sh styles/engraving/demo/build.sh my_content.json (TTS + whisper check, events, score re-placed from the events, mix, cue check, subtitles, frames). To keep the main film untouched, sh styles/engraving/demo/tools/build_alt.sh my_content.json builds everything in demo/out/alt/ instead (the demo's content_alt.json, 2 details, 35.6 s, passes the cue check).

Minimal example:

{
  "title": "The Great Scallop", "latin": "Pecten maximus", "plate_no": "Pl. XII",
  "series": "Shore Gallery · Shells of the Atlantic Coast", "subject": "scallop",
  "details": [ { "name": "Hinge", "latin": "umbo", "note": "The oldest part of the shell.", "focus": "umbo" } ],
  "colors": [ { "region": "shell", "color": "#d98a5c" }, { "region": "bands", "color": "#a8423a" } ],
  "caption": "Hold a real shell at the Discovery Table",
  "voice": { "voice": "bm_fable", "speed": 0.92, "lines": [ { "id": "title", "text": "Plate twelve. The great scallop." } ] }
}

Swapping this file and running build.sh checks that the engine re-flows; it is not how a user's film is made.

Engine reference

import { B, engraveShape, Wash, drawSheet, engraveText } from './engine/index.js';

// 1. any shape + a light direction → an engraved figure (contour lines follow the form), cut in order
const { ink, shape: spark } = engraveShape(
  'M0 -120 C12 -40 40 -12 120 0 C40 12 12 40 0 120 C-12 40 -40 12 -120 0 C-40 -12 -12 -40 0 -120 Z',  // a four-pointed spark
  { at: B.xf(860, 560, 1.9), light: [-0.6, -0.7], spacing: 4.2, style: 'contour' });               // or style: 'hatch'
engraveShape('M0 0 H150 V26 H0 Z', { at: B.xf(1140, 740, 1), ink, g: 't' });                        // its cursor tail, same ink
ink.schedule(['ol', 'tol'], 0, 1.1, { conc: 2 }); ink.schedule(['h1', 'th1'], 0.8, 2.2, { conc: 40 });
ink.schedule(['h2', 'th2'], 1.6, 2.7, { conc: 40 }); ink.schedule(['h3', 'th3'], 2.2, 3.0, { conc: 40 }); ink.build();

// 2. the "only colour": hand-colour one element and leave everything else in black ink
const w = new Wash({ scale: 1.5 });
w.add({ path: spark.path, polys: spark.polys, color: '#D97757', origin: [860, 560], t0: 3.0, dur: 1.2, alpha: 0.85 });

window.render = t => {
  drawSheet(ctx);                 // paper, plate tone, plate mark
  w.draw(ctx, t);                 // colour under the ink (omit for pure black-and-white)
  ink.draw(ctx, t);               // everything cut by time t; lines being cut grow
  engraveText(ctx, 'THE SPARK.', 960, 170, { size: 50, weight: 600, track: 0.16, p: t - 1.5 });
};

Runnable as demo/example/index.html (node core/render/still.mjs styles/engraving/demo/example 4.5), output in demo/stills/engine_example.jpg.

Main functions:

Function	What it does	Key parameters
`B.shape(d, xf)`	SVG path → world rings + Path2D	`xf(x, y, scale, rot, flip)`
`B.Ink`	ordered, width-bucketed stroke store	`group(name)`, `schedule(group, t0, t1, {conc})`, `instant(group)`, `draw(ctx, t, {color, wScale, dx, dy})` → tips being cut
`B.hatch(ink, polys, o)`	one family of swelling lines bent to the form	`angle, spacing, bend, tone(x,y), thr, wMin, wMax, swell, excl`
`B.engraveTone(ink, polys, o)`	the engraver's three passes	`angle, cross, third, t2, t3, g`
`B.formTone(polys, {light})`	any shape → pillow-lit tone field (+ `.df` distance)	`light, lz, base, radius, rim`
`B.contourHatch(ink, polys, o)`	lines following the form (iso-distance contours)	`spacing, tone, thr, wMax`
`B.outline / B.stroke`	swelling contour / open burin stroke	`w, light, vary, run, pinch, swell, excl`
`B.stipple`, `B.fur`	dots by tone; combed hair flicks	`density, r, tone` / `len, dir(x,y), curl`
`B.sphereTone`, `B.cylTone`, `B.linTone`, `B.blobTone`	analytic tone fields	light from `B.LIGHT`
`Wash`	hand colouring, cached per region	`add({path, polys, color, alpha, origin, t0, dur, spill, offset, lift, pool})`, `draw(ctx, t)`
`drawSheet`, `borderInk`	paper, plate tone, bevel; ruled border as ink	`plate: [x0, y0, x1, y1]`
`engraveText`, `writeScript`, `wrapLines`	cut roman lettering; written script; fixed-size balanced wrap	`size, weight, italic, track, align, p`
`roundelFrame`	double-ruled circle scribed by `p`	`x, y, r, p, w`
`Copper.drawCopper / copperLight / drawGrooves / drawBurin / drawSwarf`	the copper close-up	`zoom, lift, skew, s`

A minimal runnable example of the whole thing is demo/film.js with content_alt.json (a different subject, two details).