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The Ostwald Colour System
by Roy Osborne

The colour circle has proved a useful solution to the problem of representing the sequence of hues graphically. But hue is only one of the several distinct ways in which the character of a colour can vary. In order to relate hue to lightness, darkness and colourfulness (or saturation) of colour, investigators have devised arrangements in which the colour circle forms an equatorial ring cutting horizontally through a so-called colour solid. The vertical axis of such an arrangement (which was devised at least as early as 1611 by Aron Sigfrid Forsius, and particularly successfully by Philipp Otto Runge in 1810) serves to represent a scale from black (usually at the base) to white (usually at the top).

One such three-dimensional arrangement, which achieved popularity early in the twentieth century, was that devised by the Latvian-German scientist Wilhelm Ostwald (1853-1932), and first published as Die Farbenfibel ('The Colour Primer') in Leipzig in 1916. Die Harmonie der Farben ('The Harmony of Colours') followed in 1918.


Ostwald's colour wheel

Ostwald's colour circle consists of a sequence of 24 hues divided into eight groups of three, named yellow, orange, red, purple, blue, turquoise, seagreen and leafgreen. In his lightness scale, a standard white sample (denoted a) is linked to a standard black sample (denoted p) by 13 grey steps, judged visually to be equal in interval (and lettered b to o; the sequence is usually abridged to eight steps, a, c, e, g, i, l and p).
When organised three-dimensionally, each colour sample is located within a double cone (similar to an arrangement devised by Ogden Rood in 1879). Hues are distributed around the horizontal circumference of the double-cone, and white is at the top and black is at its base.
(Right) Ostwald's colour solid; cross-section. Colours along each line parallel to HB possess the same white content and colours along each line parallel to HW possess the same black content.

A vertical cross-section of Ostwald's double cone reveals a pair of colour sheets which are precisely complementary in colour, each a colour triangle showing graded variations of a single hue, with white at the top, black and the bottom, and with greatest colourfulness located in the third corner.

Ostwald adopted as the basis of his system a principle of psycho-physics stated by Gustav Fechner (1858) that, for all mixtures of colours, hue content plus white content plus black content equals 1 (unity). Such mixtures were worked out using methodical observations of spinning discs painted with standard sets of colours.

An Ostwald colour notation is given by a number followed by two letters which encode hue content H, white content W and black content B in the sequence HWB. The number denotes the hue, and the two lower-case letters locate the position of the colour sample on the triangular sheet. For example, the notation Ostwald 20en indicates a colour derived from Ostwald hue number 29 (mid-seagreen) and consisting of 29.4% hue content and 65.o% black content.

The Ostwald colour system remained popular for several decades following its introduction, but has now been very largely superseded by the American Munsell and Swedish Natural Colour systems. This was primarily because the original colours chosen for the system were layed out in such a way that (unlike the Munsell system) their arrangement could not be modified or extended as pigments and dyes of greater saturation were brought onto the market.

References:

Walter C. Granville & Carl E. Foss, eds. (1944), Color Harmony Manual. New York. Republished 1948 & 1958.

Egbert Jacobson (1948), Basic Color: An Interpretation of the Ostwald Color System. Chicago.

Wilhelm Ostwald (1921), Die Farbe. Leipzig. Second edition 1926.

Wilhelm Ostwald & Faber Birren, ed. (1969), The Color Primer. New York.

J. Scott Taylor (1935), A Simple Explanation of the Ostwald Colour System. London.

© Copyright 1998 Roy Osborne, All Rights Reserved
Ostwald Colour System