
Gouache is an opaque watercolour combining pigments and gum. It is available in different liquid forms as well as paste, solid and even powder.
By nature gouache is opaque and provides excellent cover, perfect for painting on coloured backgrounds.
Unlike watercolours and inks, darker tints are used first followed by paler shades. However gouache is not indelible. Strong strokes must be used to avoid bleeding of layered colours when damp.
Note also that paper too heavily charged will crack as it dries quickly.
A shiny varnish is sometimes used to alter the finished work which is naturally matte or to protect it from humidity.
Almost all non-oily, slightly absorbent papers can be used.
Usually it is advisable to use a well sized heavy paper (160g upwards) in order to avoid the deformations caused by humidity. Obviously all the watercolour papers as well as papers destined for acrylic paint and multi-technique wash-tints are suitable . Wash-tints link.
Wash tints are water based paints very similar to watercolours and often used with inks. Generally paper for water-tints should not be too slippery but as white as possible. It should not be too rigid nor too soft and definitely not too lightweight. Watercolour as well as heavier papers are very suitable.