proc_anodizing

Anodizing

finishing · anodising, Type II anodizing, Type III hardcoat anodizing

highlast updated 2026-04-26

An electrochemical process that grows an oxide layer on aluminum (and a few other metals). The layer is hard, corrosion-resistant, and porous enough to soak up dye — which is why anodized aluminum can be any color: red iPods, black laptops, gold bike-frame parts.

Electrolytic passivation: the workpiece is the anode in a sulfuric-acid bath; current grows a controlled aluminum-oxide layer (5–25 µm Type II decorative; 25–100 µm Type III hardcoat). The porous oxide accepts dye before sealing. Hardcoat raises surface hardness to ~60 HRC equivalent.

Scale & Tolerance

scale (mm)1 – 6000
tolerance (mm)0.025
skillintermediate — bath chemistry, racking, current density all matter
costlow per part at volume; capital cost moderate

Equipment

school_shopoccasionally — small DIY tank setups exist; commercial work usually outsourced
professionalcommercial anodizers with rectifiers, racks, dye and seal tanks
industrialcontinuous-coil anodizing lines for architectural aluminum

Environmental

energy_usemoderate (rectifier current)
waste_streamspent acid, dye baths, rinsewater — regulated waste streams
consumablessulfuric acid, dyes, sealing solutions

Compatible materials

Titanium Grade 1 (CP-Ti)

Titanium Grade 5 (Ti-6Al-4V)

Citations

book · Lefteri, *Making It: Manufacturing Techniques for Product Design*, 2nd ed. (Laurence King, 2012), 'Anodizing' p. 278.
standard · MIL-A-8625 — Anodic Coatings for Aluminum and Aluminum Alloys.

Your Project

A working library of materials and processes. Saves to this browser only — no account, no cloud.

Name

Stored under formatter:project. Print → Save as PDF in any browser to keep a permanent copy.

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.
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.
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.
crystalline (finish): A faceted-surface read — gemstones, glassy minerals, ice. Drives PBR defaults: IOR 2.42 (diamond), transmission 1.0, low roughness.
derive_pbr(): 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.
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: medium metalness, sheen, clearcoat.
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 entry pages. Same derive_pbr() values, real-time lit, draggable. Optional — toggle in Preferences.
material: What the thing is MADE OF. The first entity. Aluminum 6061, white oak, soda-lime glass.
metallic (finish): Specular highlight, deep shadow rim. Drives PBR defaults: metalness 1, low roughness, IOR 1.45. Polished steel, gold, copper.
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.
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.
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.

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ForMatter

Materials and processes for people who design and make things.

A local-first library of materials, processes, and applications, equal weight, citable everywhere. 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.
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 — vehicle codes through the camera, doo-wop register.
Specimen — iOS field-collection for design students.
renato.design — the rest.

Sources

Conway's Material World on raw materials, Lefteri's Making It on processes, 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. Voice blocks: Barthes, Yanagi, Benjamin channeled within their philosophy; Lefteri verbatim. All cited.

v0.5 — 2026-04-27 · Phil Renato · renato.design · MIT-licensed code, CC BY-NC research content

Preferences

Local to this browser. No cloud, no account, no telemetry.

Live Preview on entry pages Three.js shader ball replacing the static sphere. Disable on slower hardware or to keep entry pages text-only.

UI scale Browser-style zoom. Useful for classroom projection or close work.

Sphere density How many material spheres fit per row on the landing grid. Smaller spheres pack more across the page; larger ones fewer. Adapts to desktop and phone.

more fewer

Default confidence filter Search dropdown defaults to this level when the page loads.

Stored in localStorage under formatter:prefs.