A pair of complementary techniques: repoussage pushes metal up from the back side with hammered punches, chasing refines the front with finer punches and an outline-drawing tool. The Greeks did it (the Vix Krater handles, 5th century BC), the Romans did it, the Renaissance silversmiths did it, and contemporary metalsmiths still do it. The hammer mark IS the surface — every dimple a record of one strike of one tool.
The work-piece is held in pitch (a wax / asphaltum / fine-clay mixture that's solid at room temperature, soft when warmed) so the back can be worked from below and the front from above without losing registration. Punches range from broad-faced repoussé hammers (pushing volume up) through line tracers (chasing the outline) to texturing punches. Annealing between work-cycles restores ductility — silver loses its workability after 30–50% reduction without anneal.
Scale & Tolerance
scale (mm)5 – 500
tolerance (mm)0.5
skillintermediate to advanced — the technique rewards 5–10 years of consistent practice; the masters of the past spent careers in it
min skilladvanced
wheredesktopschool shop
costvery low equipment cost; high labor per piece
Equipment
school_shoppitch bowl, chasing pitch, repoussé and chasing punches (40+ punch set typical), chasing hammer
professionalas above plus pneumatic hammer attachment, programmable annealing kiln
Environmental
energy_usevery low
waste_streamminor metal sweeps, used pitch (recoverable by reheating)
sheet thickness limit (0.6–1.2 mm typical; thicker resists punching, thinner tears at the deep-push zones)
pitch backing required for support during work; the pitch must be soft enough to give and hard enough to register
work cycle alternates anneal / chase / re-anneal; cold-worked silver loses ductility past ~30 percent reduction
what is lost
hammer-mark texture is the craft register — feature in art jewelry, defect in commercial jewelry
planishing / smoothing after chasing flattens what was raised; the work is iterative and reversible during fabrication, irreversible after final polish
what is gained
high-relief sculptural form from sheet stock
figurative work in metal that no other technique produces (Vix Krater bull-handles, Hellenistic-era figural metalwork)
every mark records one moment of decision
Plain language. Neutral framing — perfection is contextual, defined by use. Cf. Winchester, The Perfectionists (HarperCollins, 2018).
Oppi Untracht (dead — channeled)
Chasing and repoussage are the techniques that record decision the way ink on paper records decision: every mark is a moment, every moment is a choice, and the cumulative sum of choices is what the viewer reads as the figure. The Vix Krater handles are not great because the metalsmith was great; they are great because every strike of every punch was — over the course of however many days the work took — the strike that the metalsmith would have made. There is no smoothing-out at the end of the process. There is no second draft. The hammer-mark IS the surface; the surface is the trace of a continuous, irrevocable, two-sided argument with the metal.
Channeled within the philosophy of Oppi Untracht (1922–2008), *Jewelry Concepts and Technology* (Doubleday, 1982), 'Repoussage and Chasing' chapter, pp. 199–250. Also relevant: Untracht's earlier *Metal Techniques for Craftsmen* (Doubleday, 1968), the bench-reference standard for silversmithing he wrote first. The Vix Krater (~530 BC, Châtillon-sur-Seine) is the canonical archaeological reference for what the technique survives at.
Silver, engraved with cast and applied decoration. Engraving attributed to William Hogarth; centre depicts George I's Second Exchequer Seal with allegorical figures.
book · Untracht, *Jewelry Concepts and Technology* (Doubleday, 1982), pp. 199–250.
Concordance
House vocabulary — terms ForMatter uses with intent.
anisotropic
Direction-dependent. Wood reads differently along the grain than across it; rolled steel is stiffer along the rolling direction. The Principled-BSDF anisotropic input rotates the highlight to match.
anodize
Electrochemical oxide layer grown on aluminum (Type II / III), titanium, or niobium. Type II accepts dye for color; titanium / niobium use voltage-driven thin-film interference instead of dye. The CMF entry covers the seal step that locks the color in.
application
What the thing IS, in the world. The third entity, peer of material and process. A water bottle, a chair, an extruded-aluminum profile.
BRDF
Bidirectional Reflectance Distribution Function. The math behind how a surface returns light for any incoming and outgoing direction. The PBR model is a parameterized BRDF.
channeled
A voice block written within a dead author's philosophy, marked and cited. Distinct from a verbatim quote. Roland Barthes channeled on PMMA reads like Barthes; the citation attributes the lineage.
CMF
Color, Material, Finish — the trio designers specify together when handing a part off for production. ForMatter's Finish entity is the F in CMF: 10 categories — polish / anodize / patina / plate / coating / texture / cut / mold_finish / glaze / stone_finish — and 100+ entries. Every finish entry pairs to the materials and processes it suits.
choral fugue
ForMatter's register. Subject stated plainly (freshman tier), answered in technical and sensorial registers, countersubjects from linked processes and applications, citations as final stretto. Voice blocks where canon attaches.
clearcoat
A second specular layer over the base surface. Glossy plastics and lacquered woods get a clearcoat term in the PBR table. IOR 1.5 by default.
compatibility (process)
Each process entry lists which materials it can work. The cross-ref renders as sphere pills so the gallery feeling extends inward.
confidence
Each entry tagged high / medium / low. A senior's low-confidence-with-three-citations beats a freshman's high-confidence-with-none. The label is a contract with the reader, not a brag.
The build's single source of truth — sphere palette + finish enum → Principled-BSDF starter values. One function feeds the entry-page table, the per-host snippets, the glTF export, and the Three.js Live Preview.
finish (entity)
ForMatter's CMF layer — surface treatments and conditions a designer chooses for a given material and process. Categories: polish, anodize, patina, plate, coating, texture, cut, mold_finish, glaze, stone_finish. Distinct from the sphere `finish` enum (metallic / matte / glossy / etc.) which is the visual register of the proxy.
freshman / senior register
Two registers in every entry — the plain freshman description and the technical / sensorial one. Same database, two readers, no extra subscription.
glTF
GL Transmission Format — the open 3D-asset standard every modern app reads. ForMatter emits a .gltf material doc per material. Open standard, designer-friendly handoff.
IOR
Index of Refraction. How much light bends entering the surface. Air 1.0, water 1.33, glass 1.5, diamond 2.42. Drives transmission and the specular term.
iridescent (finish)
Hue-shifted accent over base. Anodized titanium and niobium, opal, paraíba. Drives PBR defaults: low metalness, full iridescence, clearcoat.
iridescence
Thin-film interference layer over the base material. KHR_materials_iridescence in glTF, MeshPhysicalMaterial.iridescence in Three.js. Tunable from the FOCUS slider on iridescent / pearlescent entries. The ior and thickness range together set the visible color sweep — opal uses a 100–800 nm thickness range (film, not wavelength) to span the full visible band.
lite-PBR
ForMatter's PBR approach — Principled-BSDF starter values per entry, no measured BRDFs, no commercial assets. Honest reasonable defaults from the finish enum, per-entry numeric overrides where you have a real reason.
Live Preview
The Three.js shader ball that replaces the static CSS sphere on every entry page. One render path for every category — metals, woods, polymers, ceramics, paints, textiles, gemstones, glass. Same derive_pbr() values, real-time lit by a synthetic studio environment, draggable. Optional — toggle in Preferences.
material
What the thing is MADE OF. The first entity. Aluminum 6061, white oak, soda-lime glass.
Folded into the Project workspace at /project.html. The mood-board upload, palette extraction, character chips, and matcher results all live alongside the collected items grid and the save .formatter / save PDF / open .formatter actions — one feature, one page.
Ollama
Local-LLM scaffold on the Project page. Off by default. When toggled on in Preferences AND Ollama is reachable at localhost:11434, the natural-language input box ('something soft and warm with a wet read') asks the model to translate the description into character-chip toggles. Never invents material properties; the LLM only translates intent into existing chip vocabulary. The keyword fast-path (chips alone, no LLM) is the default — see suite-wide ai-integration pattern.
project
The full workspace at /project.html — collected materials, processes, applications, finishes plus an optional mood-board image whose dominant colors search the library for matches. Save / open .formatter files round-trip the project state. Cross-conversation: the Project page replaces the slide-down panel that used to live behind the appbar 'project' button.
patina
A chemical color shift on metal — heat-blue on steel, fume-black on silver, verdigris on copper, gun-blue on tool steel, ferric on copper. CMF-layer entry; cited by both the material and the process pages that produce it.
PBR
Physically-Based Rendering. The shading model every modern 3D app uses, parameterized by metallic / roughness / IOR / transmission / clearcoat / sheen. ForMatter publishes starter values for every material entry.
SPI mold finish
Society of the Plastics Industry mold-cavity finish standard. A1 / A2 / A3 (diamond polish, mirror), B1 / B2 / B3 (paper, semi-gloss), C1 / C2 / C3 (stone, matte), D1 / D2 / D3 (dry blast, textured). The finish prints from the mold cavity onto the molded part — a designer picks the SPI grade with the molder when specifying the tool.
Principled BSDF
Blender's name for the consolidated PBR shader. Most other apps ship the same shader under different names (Standard Surface, ShaderGraph, Substance). One node, every output.
process
How the material is MADE INTO the thing. The second entity. Cast, machined, kerf-bent, anodized, planished, granulated. Process is a peer of material, not a footnote.
quote
A voice block carrying a verbatim quotation from a living author, with citation. Distinct from a channeled block. Living = quote only; the rule is enforced at the schema layer.
roughness
Microsurface scatter. 0 is mirror-smooth; 1 is fully diffuse. Most real surfaces sit between 0.2 and 0.8.
sphere proxy
ForMatter's visible-character stand-in for every material. CSS-gradient driven by the entry's palette and finish, not a baked render. Honest about being a proxy, scales to six hundred entries cheaply, tweakable in one place.
substitute
A peer material that could fill a similar role. Cross-references render as sphere pills inside an entry — the gallery feeling extends inward.
transmission
How much light passes through. 1 is fully transparent; 0 is opaque. Glass, gemstones, clear plastics carry transmission.
PVD
Physical Vapor Deposition — vacuum-chamber sputter or cathodic-arc deposition of a thin ceramic film onto a metal substrate. The CMF-layer's modern coating chemistry: TiN (gold), ZrN (champagne), CrN (pewter), TiCN (warm bronze / rose-gold), AlTiN (charcoal-anthracite, near-black), DLC (deep black). Hard, doesn't tarnish, paint-thin.
VDI 3400
German engineering reference standard for mold-cavity texture (Erodieren bearbeitete Werkstückoberflächen). The full scale runs reference plates 0–45 by Ra value; production specs typically draw from 12–45 because plates 0–11 require diamond-mirror polish on the mold cavity and are rarely commissioned in commercial tooling. Pairs with the SPI standard; both define what gets cut into the mold.
voice block
A versal block where a real authored voice attaches to the material or process. Schema-tagged with status (living / dead) and mode (quote / channeled). Citations always.
woodgrain (finish)
Directional sheen with grain ring. Drives PBR defaults: anisotropic 0.6, medium roughness, no metalness. Every wood entry.
Press ⌘⇧/ to open this panel from anywhere · Esc to close.
ForMatter
Materials and processes for people who design and make things.
A local-first library of materials, processes, applications, and finishes — equal weight, citable everywhere, with cost-over-volume curves, trade-off profiles, equipment-tier filters, and second-life paths layered onto the data so a student can move from "what is this" toward "what's actually buildable here, now, by me." Part of the renato.design ecosystem — sibling of Plenum, Specimen, Ingenue, gesture, graf, and the Renato Rhino plug-ins. Form and matter, inseparable.
Why this exists
Half of teaching materials is teaching how the material is made into the thing. The standard subscription library was always light on that half. The wedge here isn't better samples or a prettier interface — it's treating Process as a peer entity, not a footnote.
Rules of the house
Citations or it didn't happen. Every property number, every claim, every borrowed register has a traceable source.
Living authors are quoted only. Verbatim or not at all.
Dead authors may be channeled within their philosophy — marked, cited, never impersonated.
Permalink or nothing. Museum holdings link to the specific collection-record URL. Designer overview pages, press releases, and exhibition listings don't qualify.
Relative, not absolute. Cost, lead time, and other figures that age get published as ratios and ranges. Crossover points beat magnitudes.
Confidence labeled honestly. A senior's low-confidence-with-three-citations beats a freshman's high-confidence-with-none.
Local-first. Works offline, no login, no subscription.
Sister apps
Ingenue — five voices argue about what to build from electronic parts. Where ForMatter teaches what the thing is made of, Ingenue proposes what the thing could be.
Plenum — VIN, fender-tag, and broadcast-sheet decoder for muscle and pony cars; doo-wop register.
Specimen — iPhone 3D scanner that treats the captured object as a specimen, with voiced commentary.
Conway's Material World on raw materials, Lefteri's Making It on processes, Forty's Concrete and Culture, Sparke's Design in Context, Bürdek's Design: History, Theory and Practice of Product Design, Schröpfer's Material Design on materials in architecture, Winchester's The Perfectionists on tolerance, Minshall's Your Life Is Manufactured on the global supply chain, von Busch's Making Trouble on material activism, Were's How Materials Matter, Hegger / Drexler / Zeumer's Basics Materials, Untracht and McCreight on metalsmithing, USDA Forest Products Lab on woods, GIA on gemstones, Schott / CoorsTek / Toray / Owens Corning datasheets, MakeItFrom for verifiable property numbers, ASM Handbook, ISO standards. Museum holdings draw from the Met, MAD, V&A, Smithsonian American Art Museum, Newark Museum of Art, British Museum, Heard Museum, Smithsonian NMAI, Eiteljorg Museum, Philadelphia Museum of Art, Cranbrook Art Museum, and Grand Rapids Art Museum — collection-record permalinks only, designer overview pages and exhibition listings excluded. Voice blocks now ride on every entry kind — material, process, application, and finish — and include Ruskin on iron, Anni Albers on twining, Greg Lynn on the shred-and-teeth NURBS lineage, Pugin on the metal that won't be hammered, Barthes / Yanagi / Benjamin channeled within their philosophy; Sparke, Bürdek, Forty, Conway, Schröpfer, Minshall, von Busch, Lefteri, Pat Pruitt, Mary Lee Hu, Tom Joyce, Albert Paley, and the rest of the contemporary makers quoted verbatim with citation. All cited.
v0.6.83 — 2026-06-01 · Phil Renato · renato.design · MIT-licensed code, CC BY-NC research content
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