About these notes

These notes were written by Michael Menke. They began as a long paper on how paints mix, and this site is that paper rewritten as lessons for painters.

Where the numbers come from

  • Golden’s spectral data. Golden Artist Colors measured the reflectance of 78 of its Heavy Body acrylics straight from the tube, as thick drawdowns over a white card [24]. The paint table lists them, with the pigments and opacity ratings from Golden’s pigment chart [25].
  • Okumura’s tint ladders. Okumura, at the Rochester Institute of Technology, measured 26 of the same colors from Golden’s Matte Fluid line mixed with more and more titanium white [59]. These are the calibrated paints.
  • The white. The reflectance of Golden’s titanium white comes from the Art-SI library at RIT [71], and the way it scatters each color from measurements of rutile at the Lawrence Berkeley laboratory [42], [43].
  • The eye. The cone sensitivities are Stockman and Sharpe’s [70], and the color calculations follow the CIE’s standards [11].

The model

Only the 26 calibrated paints are ever mixed here. For each of them, the model reads the absorption from Golden’s measured masstone and fits how strongly the paint scatters light to Okumura’s measured tints. It then computes any mixture with the two-constant Kubelka–Munk law. It reproduces Okumura’s tints to about one unit of color difference on average, about the smallest difference a careful observer can see side by side. Section 2.6 explains how it works and where it is least certain.

Every paint measured here is an acrylic. The physics in these notes applies to oil paint as well, but the measured numbers belong to these acrylics.

The paint tools

The paint tools run the same model in your browser, with the same data. A screen can only approximate a paint color, and the most vivid paints lie outside what a monitor can show (Section 1.8), so trust the numbers more than the swatches.

The PDF

The whole of these notes, with the math gathered at the end of each part, is also available as one PDF: Color Science Notes.

All sources are in the references.

Back to top