Costs are kept to an economical level by replacing some of the more costly pigments with less expensive alternatives. Pigments derive from a number of sources: Some are natural products, notably the earths, eg. umbers, ochres; others come from metal compounds and are sometimes termed ‘traditional’ or ‘genuine’, eg. ultramarine.
The distillation of petroleum yields an ever widening range of organic pigments which are often termed as ‘modern’. Many of the pigments used in Cotman are organic.
The range of 40 colours are chosen according to mass tone (colour from tube), undertone (bias of colour when in a thin film), colour strength, relative opacity and the character of the pigment itself. The resultant colour spectrum ensures the largest number of colours can be mixed.
The Cotman Water Colour range has a more uniform consistency than the Artists’ Water Colour range and this benefits beginners as there is less to learn about each individual pigment. The Cotman Water Colour range also relates to the Winsor & Newton Artists’ Water Colour range, e.g. Burnt Sienna in both ranges has the same hue. This enables artists to use colours from both ranges with minimal adjustment to their technique.
As water colour films are so thin all colours appear more or less transparent when painted onto paper. The pigments used in Cotman are also predominantly transparent.
As a general statement the traditional pigments granulate, e.g. earths, ultramarine. The modern organic pigments do not, e.g. Cotman hue colours. If you wish to avoid granulation in your painting, the use of distilled water can reduce it, particularly in very hard water areas.
In Cotman Water Colour, AA and A are regarded as permanent for artists’ use. To be sure of the permanence of any colour, please refer to the ratings on the colour chart or Cotman tube/pan labels
“Hue” means colour and indicates that a modern pigment has been used instead of the traditional one. For example, ‘Cadmium Red Pale Hue’ in Cotman Water Colour is a ‘colour of cadmium red pale’. A hue colour is not necessarily inferior.
Both Cotman and Artists’ Water Colours can be freely intermixed. If long term permanence is required with Cotman, use only colours rated AA or A which are recommended as permanent for artists’ use. The three primary colours in Cotman Water Colour are Lemon Yellow Hue, Ultramarine and Permanent Rose. If using a six colour mixing system we would recommend Lemon Yellow Hue, Cadmium Yellow Pale Hue, Ultramarine, Intense Blue, Permanent Rose and Cadmium Red Hue.
Traditionally the white of the paper provides the brilliance to water colour and can be used as highlights. However, some artists utilise Chinese White for highlights at the end of their painting or in dulling some colour mixtures down.