A tenmoku variant where the iron precipitates as visible silver-gray spots scattered across the deep-black glaze surface — like droplets of oil on water. The most prized of the tenmoku family historically; surviving Song-dynasty oilspot bowls are National Treasures of Japan. Reads as a black night sky with metallic stars.
Same iron-saturated feldspar base as plain tenmoku (8–14% Fe₂O₃) with peak temperature held longer to allow iron crystals to nucleate at the glaze surface. Crystal size 0.5–3 mm; appearance silver-gray to gold-iridescent depending on crystal thickness and atmosphere. Cool-down rate matters — too fast and crystals stay sub-visible; too slow and they overgrow into hare's-fur streaks. Modern American studio firings (recipes from David Schaller, John Britt) use cone 10 reduction with a 30-minute hold at peak, then slow cool through the crystallization range (1180–1100 °C). One of the harder glazes to control reproducibly.
character — silver-spotted black, oil-on-water surface, hard-to-reproduce, museum-tier register.
Robin Hopper The Ceramic Spectrum (Krause, 2nd ed.); Daniel Rhodes Clay and Glazes for the Potter.
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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