The Scratched Wall

Sgraffito is plaster laid in coloured coats and scratched back while still wet, so the lower colours show through. This wall has three coats: ochre at the back, then terracotta, then lime white on top. The scratching is not drawn. Two chemicals diffuse through the wet top coat and react with each other (the Gray–Scott model), and the scraper cuts wherever chemical V passes a threshold. Spots, worms and labyrinths emerge, like the frustule pores of diatoms, depending on two feed rates. Drag to seed more reaction. Each cutting pass is a reservation on the ledger.

LIT: sgraffito is a Renaissance façade technique (Florence, 15th–16th c.) with roots in pottery slip-scratching. The Gray–Scott model (1983; Pearson's 1993 classification) gives spots and stripes for different feed (F) and kill (k) rates. ANALOGY: diatom pores are made by silica biology, not by reaction–diffusion of this kind.

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