Chemical Description: Cadmium zinc sulphide, Cadmium sulphoselenide
Colour index name: PY 35, PR 108
Colour index number: 77205, 77202
Permanence rating: A
ASTM Lightfastness Rating: I
Transparency/Opacity: O
Good quality gouache colour is a combination of pigment and gum arabic. Gum arabic is the binder that holds the pigment, giving it that perfect creamy 'flowing' consistency. (NB some cheaper brands may have chalk added to the pigment which in turn effects the 'flow and the brilliance of colour'). As a result of the high level of pigmentation Winsor & Newton Designers Gouache dries to a matt finish. This reduces the reflection when photographing the work.
Every colour within the range has an individual formulation to take advantage of each and every pigment characteristic and ensure tube stability.
One of the natural attributes of gum arabic - the binder used in Designers Gouache is that it is quick drying. This faster drying allows quick working techniques and preliminary sketching to be done. Also as with water colour, work can be finished quickly and as a result travelling with work is made much easier.