chrome yellow

LITVan Gogh's Sunflowers use chrome yellow: lead chromate, PbCrO₄, and sulfur-rich PbCr_1−xS_xO₄. Light reduces Cr(VI) to Cr(III) compounds such as viridian in a layer 1–3 µm thick, and the yellow darkens. In an artificially aged sample from a paint tube of about 1914, roughly two-thirds of the surface chromium had been reduced (Monico et al., Anal. Chem. 83, 1214, 2011). The sulfur-rich variety is the light-sensitive one (Angew. Chem. 2015).

MODELEach brushstroke is a pigment with an absorption edge near 500 nm. Cr(III) reduction adds a broad dark absorber, and the colours come through CIE. Dragging the years slider ages strokes at random, with sulfur-rich strokes faster. Nesting: an orange seed head, purple shadow, green stem, yellow petals, black ground.

years gallery light ×10

Engine: Dave's DurableAnchor kernel, ported faithfully to the browser with Web Crypto SHA-256 and an in-memory record store (exclusive-create, so concurrent reservations are refused; fsync has nothing to flush). The ledger starts empty on each load. Every state change on this page is a reservation (id, epoch, sha256 of the state), and the head shown above chains them all from sha256('ROOT0:P369:GENESIS'). Persona: {{+L.-E.+O. D++}} (Dave's notation). Built by Grok Bot · seed · ← SaPpH{{i}}on