Composition and Permanence Terms Explained
Below each heading you will find descriptions which will explain the
terms used in the Composition and Permanence Tables of each colour
This colour code column indicates the code number that is given to each
of the colours. This is primarily for ease of reference for retail and
catalogue purposes and to assist you in purchasing your materials.
This is the colour name, eg. Permanent Alizarin Crimson.
This column provides the chemical description of the pigments used in each colour. This is often useful for conservators.
The Colour Index International is the standard compiled and published
by both: The Society of Dyers and Colourists, and the American
Association of Textile Chemists and Colorists. The Colour Index
classifies pigments by their chemical composition. This information
will allow you to research a specific pigment's working characteristics
in reference books if you wish. The individual pigments are identified
in two ways.
Each pigment can be universally identified by its Colour Index Generic
Name. As an example: Cobalt Blue is Pigment Blue 28, abbreviated to
Although the working properties of Winsor & Newton colours are
fully detailed in our literature, we publish the Colour Index Generic
Names of the pigments to allow you to cross reference the working
properties in other sources if you wish, e.g. lightfastness, opacity,
toxicity, etc. The Colour Index Generic Name is particularly necessary
to fully identify some of the modern pigments. The disclosure of a
pigment as Naphthol Red is insufficient because there are over a dozen
different types, differing widely in lightfastness and opacity.
- Colour Index Number - C.I. No.
Pigments can also be identified by their Colour Index Number. It is
considered an additional source of information to the Colour Index
Generic Name. As an example: Cobalt Blue is 77346.
Of the two methods of reference, The Colour Index Generic Name is most commonly used.
The Series number of a colour indicates the relative price of the
colour and is determined mainly by the cost of the pigment. Series 1 is
the least expensive and Series 6 the most expensive. Where there is no
series column, this indicates the price is uniform across the range.
The permanence of an artists' colour is defined as ‘its durability when
laid with a brush on paper or canvas, graded appropriately and
displayed under a glass frame in a dry room freely exposed to ordinary
daylight and an ordinary town atmosphere'. This definition reflects the
manner in which we expect to find paintings displayed. However, for
testing purposes we are also able to utilise accelerated tests for
lightfastness and binder stability, in addition to the information
issued by our pigment suppliers.
Winsor & Newton ratings are therefore a combination of the natural
passage of time, accelerated tests and pigment manufacturers' testing
and development and are the most stringent in the industry.
AA - Extremely Permanent
A - Permanent
B - Moderately Durable
C - Fugitive
For further information on some colours, the rating may include one or more of the following additions:
(i) ‘A' rated in full strength may fade in thin washes
(ii) Cannot be relied upon to withstand damp
(iii) Bleached by acids, acidic atmospheres
(iv) Fluctuating colour; fades in light, recovers in dark
(v) Should not be prepared in pale tints with Flake White, as these will fade
- (vi) ‘A' rated with a coating of fixative
The ASTM abbreviation stands for the American Society for Testing & Materials.
This organisation has set standards for the performance of art
materials including a colour's lightfastness. To measure lightfastness
using this system, colours are reduced to a level of 40% reflectance by
the addition of Titanium White, (except for water colour which relies
on the white paper). This means the amount of light reflected from the
colour swatch. The swatches are then tested in both sunlight and
artificially accelerated conditions.
The results allow each colour to be rated on a scale from I - V
depending on the medium. In this system I is the highest lightfastness
available though both ratings I and II are considered permanent for
Where no ASTM rating is given for a Winsor & Newton colour, it is denoted as N/L
meaning "Not Listed" this usually indicates that the pigment or the
type of range has not yet been tested by the ASTM. It does
not necessarily indicate a lack of lightfastness.
In these cases it is recommended that the Winsor & Newton
permanence rating, which is the rating system evaluating colour on many
aspects including lightfastness, should be used to indicate a colour's
ability to resist fading.
T/O - Transparency/Opacity
The transparent colours are marked ‘T', semi-transparent ‘ST'.
The relatively opaque colours are marked ‘O', semi-opaque ‘SO'.
Transparency however is relative and the ratings are provided as a
guide only. In addition, any thin film of colour will appear more
transparent than a thicker one.
G/St - Granulating/Staining
In water colour, some colours show a tendency to granulate and are
marked as ‘G'. Many artists use granulation to add visual texture to
As a general statement the traditional pigments granulate, e.g.
cobalts, earths, ultramarines. The modern organic pigments do not, e.g.
Winsor colours. If you wish to avoid granulation in your painting, the
use of distilled water can reduce it in very hard water areas. Those
colours not marked ‘G' will tend to give a more uniform wash.