A multi-layer billet of dissimilar metals — silver and shakudō, copper and gilding metal, palladium and white gold — diffusion-bonded into a stack, twisted / drilled / forged to expose layer cross-sections, then patinated to color each layer differently. The surface reads as polished wood grain rendered in metal. Originated in 17th-century Japanese sword fittings; carried into modern wedding-band work by Tiffany & Co. and studio metalsmiths.
Sequence: stack 8–25 thin sheets of dissimilar metals (~0.4–1.0 mm each) clamped between graphite plates; diffusion-bond at ~75% of the lowest melting point, ~20 MPa pressure, 10–30 min in reducing atmosphere or vacuum. Forge / roll / drill / grind the billet to expose layer geometry on the surface. Etch with an acid that selectively colors each metal — ferric chloride for copper, ammonium persulfate for silver, rokushō (copper acetate) for shakudō and shibuichi alloys. Modern Western work uses palladium / white-gold / red-gold combinations etched with selenium-based jewelry patinas. Repeat etch cycles intensify color and depth. Modern precious-metal shops bond solder-free by solid-state diffusion: layers are ultrasonically cleaned, clamped under pressure (a hydraulic press or a dedicated jig), and fired in a kiln packed in hot powdered charcoal to keep oxygen off the bond line (a separate later step — ring-blank annealing — uses an argon-flooded chamber instead). James Binnion, Andrew Nyce, and Stewart Grice's 'thermal expansion mismatch torque plate' (TEMTP) system is a documented refinement of the clamping jig aimed at these bond-quality problems, tested with hardness/tensile measurements and diffusion-zone metallography on 14k yellow, red, and palladium-white gold billets. After bonding, the billet is thickness-reduced 30–60% by drop hammer before carving and pattern-forging.
character — fluid wood-grain pattern in metal, polychrome at depth, archival, classical-Japanese register.
Hughes & Rowe The Colouring, Bronzing and Patination of Metals (Crafts Council, 1991, Watson-Guptill ed. 1995); American Institute for Conservation patina-conservation guidelines.
House vocabulary — terms ForMatter uses with intent.
Materials and processes for people who design and make things.
A local-first library of materials, processes, applications, and finishes — equal weight, citable everywhere, 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.
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.
Conway, Lefteri, Forty, Sparke, ASM, GIA. Every voice: Voices.
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