Tongan ngatu is barkcloth built from pasted feta'aki paper-mulberry strips, laid over carved kupesi design boards so that dye rubbed across the surface transfers the pattern as grainy, repeated registers — rubbed, never painted. Two earth dyes carry the whole language: red-brown koka from Bischofia bark juice and tongo black from mangrove and candlenut soot.

Red and black on a light tan bark ground are the fundamental Tongan colours, symbolising male and female. This system distills that two-colour, matte-cloth tradition into a digital design language of bold rubbed bands and beaten-bark texture.