Study: one hundred wash squares, and what they teach you
A hundred-square chart takes about two hours and it changes how you mix colour permanently. Not because the individual squares are informative — most of them are not — but because the chart shows you where the useful ratios are and how narrow those bands actually are.
Neutral — Greys mixed from complements, never from black.
| Pigment | Parts | Hex |
|---|---|---|
| French Ultramarine | 2 : 6 (33%) | #2E4A7D |
| Burnt Sienna | 2 : 6 (33%) | #9A5A32 |
| Winsor Yellow Deep | 1 : 6 (17%) | #D9A02B |
| Quinacridone Rose | 1 : 6 (17%) | #C2537A |
- Rule a 10 x 10 grid of 2.5 cm squares on A3 cold press 200 gsm. Twenty minutes of ruling saves an hour of confusion later.
- Choose four pigments only. Write their names along the top edge and the left edge of the grid, in pencil.
- The diagonal squares from top-left to bottom-right are single-pigment squares at ten different concentrations, from 1% to 100%.
- Every square above the diagonal is a two-pigment mix at the concentration given by its column, mixed with the pigment named by its row.
- Fill one row per session. Do not try to complete the chart in one sitting — fatigue shows as inconsistent load after about row six.
- Label each square with the actual ratio in pencil on the paper, not in a separate notebook. Notebooks get separated from charts.
- When it is finished, laminate it or keep it in a clear sleeve. This chart will be the most-referenced object in your studio.
Why four pigments and not twelve
A four-pigment chart has 10 single-pigment squares and 90 two-pigment squares. A twelve-pigment chart has 144 single squares and 15,000 possible pairs, which is neither finishable nor readable. Four is the largest number that produces a chart you will actually complete and actually use.
Choose pigments that cover the wheel unevenly. French ultramarine, burnt sienna, winsor yellow deep and quinacridone rose between them produce usable greens, oranges, violets and a full range of neutrals, which is as much coverage as four tubes can give.
The concentration axis is the important one
Most home-made colour charts vary the ratio between pigments but hold the concentration constant, which means they teach you almost nothing about how the paint actually behaves. Varying concentration along one axis and pigment identity along the other exposes the thing that matters: a change of one part in four at 80% load is nearly invisible, and the same change at 8% load is a completely different colour.
That asymmetry is the single most useful fact in watercolour mixing, and it is visible in one glance at a properly built chart.
Where the chart stops being useful
Below about 3% load the differences between squares become invisible on a chart and remain invisible on paper, so the last few concentration columns are wasted. Stop the concentration axis at 3% rather than at 1% and use the extra columns for a fourth and fifth pigment row instead.
Also note that the chart is only accurate for the paper it was painted on. Granulating pigments behave entirely differently on hot press, so a chart made on cold press is misleading for a hot press painting.
What matters
- Four pigments maximum: 190 squares is a chart you finish; 15,000 is one you abandon.
- Vary concentration on one axis and pigment identity on the other — ratio-only charts teach nothing about behaviour.
- One part in four matters enormously at 8% load and hardly at all at 80% load.
- Stop the concentration axis at about 3% and use the saved columns for more pigments; the chart is only valid on its own paper.
Handling note — Technique notes only. Follow the manufacturer's safety data sheet for pigment handling and studio ventilation.