Composition and Permanence Terms Explained

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 range.

Code
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.

Colour Name
This is the colour name, eg. Permanent Alizarin Crimson.

Chemical Description
This column provides the chemical description of the pigments used in each colour. This is often useful for conservators.

Colour Index
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 Colourists. 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.

• Colour Index Generic Name - C.I. Name

Each pigment can be universally identified by its Colour Index Generic Name. As an example: Cobalt Blue is Pigment Blue 28, abbreviated to PB28.

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.

Series
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.

Permanence
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

ASTM
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 artists' use.

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 their paintings.

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.

Again in water colour, the modern organic pigments, eg. the Winsor colours, are made of very fine particles which cause them to stain the paper. These colours cannot be lifted completely with a damp sponge and are marked ‘St' in our literature. The traditional colours tend to lift from the paper more easily. Staining in water colour should not be confused with bleeding in Designers' Gouache.

Bl - Bleeding
In Designers' Gouache, some colours made from soluble dyes may bleed through superimposed colours. These colours are marked ‘Bl' in the literature.

Binder
The type of binder used for the colour. The binder for pastels is not disclosed.

Using the tables
The information for each colour and even the colour name may vary from range to range.

Refer to the range you use and look up the colour in that table.