A design book in the search for a chair · prototype edition

The Hundred-Year Chair

Designing atoms in the age of bits.

A chair lasts by being lovable, legible, and maintainable. Wanted enough to be kept, clear enough to be understood, easy enough to keep up: those three make a chair lasting. Standardization does not. Everything here, the geometry, the joints, the finish, the mark, serves the three, and the one they cannot guarantee, that the chair is truly lovable, is the project’s honest risk.

Kratstoel, Gerrit Rietveld, 1934, white-painted period example — Krat-stoelGerrit Rietveld, 1934. Priced to the guilder; drawn to be built by its buyer. Photo: Centraal Museum Utrecht.

The ten-dollar replica in black film-faced plywood with the wide 100 mm arms, 2026 — The ten-dollar replicaThe same drawing, rebuilt from salvage in 2026, carrying the wide arm of the museum’s own 1934 chair rather than the sheet’s narrow one. In ply the split that punished that arm in pine cannot propagate.

Vilbert chair, Verner Panton for IKEA, c. 1993 — VilbertVerner Panton for IKEA, c. 1993. Four panels, briefly produced; the fruitful error that started the search. Photo: dealer listing, Pamono.

The Keel Chair in side elevation against a grey backdrop: black film-faced plywood back, seat and tie panels seen edge-on with their pale ply edges showing, a cherry keel running as one long diagonal from the top of the back down to the floor, and a pale plywood front leg crossing it — Keel ChairThe search led to the Keel Chair, embodying the pattern of two congruent triangles sharing a keel. Black film-faced plywood on a cherry spine, photographed 7 September 2026.

Build · the atoms

The Pattern

Three chairs built to one geometry, each with its drawings and its cut list: Rietveld’s 1934 crate lounge, the Keel Panel on its hardwood keel, and the Keel Truss pinned at the arm. Free to build, free to improve; a chair conforms by passing the tests, not by resembling the drawing.

The Hundred-Year Chair — Designing atoms in the age of bits, by Karl T. Ulrich

Verify · the weeds

Technical Notes

The details the narrative keeps out: why bolted joints go slack, how wide the keel has to be, doing mechanical CAD by conversation. Every claim says whether it is verified, standard, derived, or unverified.

Instruments: the Fan (a century of seat-and-back geometry) · the Timeline (watch the design walk from the Vilbert to the truss) · the Gallery (the workshop record in photographs) · the Lineage (the family tree, dated against the tape) · the Tape (the collaboration itself, measured: bouts, tokens, bits and atoms) · the Ledger (every open verification item, in one place)

The Hundred-Year Chair · hundredyearchair.com · prototype, August 2026. Every figure on this site is generated from the same scripts that cut the chair; where a value is estimated rather than measured, it says so. The four photographs above are the pedigree in the flesh; the scale drawings live on in the timeline. Archival material: Centraal Museum Utrecht, Rietveld Schröder Archive.