The Dictionary names every pattern in a simplified six-colour vocabulary — white, black, red,
green, yellow, blue, "the rest are shades of these six." These are not screen primaries
(tartans are not woven in #FF0000); they are representative cloth shades, chosen to maximise
discrimination — to keep the colour distinctions that genuinely separate one tartan from
another and throw the rest away. This post re-anchors those six onto the fine
grid and re-runs the experiment that picked them.
The six, as grid points
Each colour is now a point on the fine grid, with a level-ring-hue address. Black and white
are fixed: black at the lattice black cap, white as the cream one level below the white cap.
| colour | grid code | hue | |
|---|---|---|---|
| W White | #F7F7F7 | 39-00 | — (near-white) |
| K Black | #000000 | 00-00 | — (black cap) |
| R Red | #CC0000 | 21-09-05 | 32° |
| G Green | #006100 | 17-06-15 | 142° |
| Y Yellow | #F2BF00 | 33-07-11 | 90° |
| B Blue | #2A418A | 16-05-23 | 267° |
Why these, and not others
Two searches were run against the grid and the full corpus of ~19,000 setts, and they agree.
Black and white are the natural extremes. Spread points across the dyeable space to maximise separation and the first two it chooses are the black and white caps — they are literally the farthest-apart pair. Fixing them does not override the geometry; it formalises it.
Red, green and blue fall out on their own. The next three points a max-min spread picks are blue, red and green — almost exactly the old anchors. Independently, clustering the corpus's vivid stripes by how much thread is dyed each colour gives the same three as its largest masses (green 35%, blue 31%, red 26%).
Yellow is the cultural sixth. Geometry does not volunteer yellow: its colours are light, so a vivid yellow sits perceptually close to white, and white has already claimed that corner. The maximally-distinct sixth colour would be a dark brown or a purple. Yellow earns its place in the vocabulary because tartan uses it — it is a genuine, distinct dye cluster (about 8% of vivid thread), just a smaller one than its neighbours. It is the colour the six keep for recognition rather than for separation.
So the old hand-placed anchors turn out to be right where they should be: their hue positions are confirmed by both the geometry and the cloth, and they are now exact lattice points rather than free-floating values — the reference every shade is read against, and the precursor to a larger mid-range palette of named colours.