Colour Index 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.
Series: The Series number 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 5 is the most expensive. Where there is no series column, this indicates the price is uniform across the range.
T/O - Transparency/Opacity: Transparent colours are marked ‘T' and semi-transparent ‘ST'. Opaque colours are marked ‘O' and 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.
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'.
In simpler terms, their resistance to change when exposed to light and the atmosphere.
- 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
Lightfastness: Lightfastness is shown with an ASTM rating for the pigment. The ASTM abbreviation stands for the American Society for Testing and Materials. This organisation has set standards for the performance of art materials including a colour's lightfastness. In this system, I is the highest lightfastness available and V is the lowest, 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 labeled 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, we recommend that you refer to the Winsor & Newton permanence rating, which evaluates colour on many aspects including lightfastness and is used to indicate a colour's ability to resist fading.