Gesso Paint (Coloured Gesso) - A ProChroma Super Hack
White Acrylic Gesso's tooth and absorbancy is most commonly derived from the powdered mineral dust it contains, the commonest being from calcium carbonate (a type of naturally occurring chalk), or, Gypsum (calcium sulphate) and/or calcite (crushed marble dust), along with titanium white pigment which gives it that bright white colour and great covering power. These ingredients are suspended in a high quality acrylic resin that offers the necessary bonding and priming power.
Tinting gesso with acrylic paint and using as an 'imprimatura' (stained/toned ground) has been common practice for artists for as long as acrylics have been a popular medium. Most acrylic paints however lack the pigment load to fully saturate the gesso with strong colour as they already have a binder content that prevents pigment load from exceeding a certain binder to pigment ratio threshold.
When using white acrylic gesso with ProChroma pigments, it acts as the perfect opaque-white binder to which colour can be added to make a high coverage paint. Having no binder, our colours can reach pigment saturation levels that effectively overpower even the strong white of the gesso, whilst retaining the opacity.
The resulting paint has a very matt finish that at first glance resembles gouache but, with that slightly toothed surface texture of gesso. It can therefore be used as a combined primer/underpainting and painted on with gouache or acrylic paint, or drawn on with coloured pencil, crayon or oil pastel to great effect,
Gesso paint makes perfect scenery paint for murals or theatre backgrounds, as its extra matt finish reduces glare and sheen from lights.
We highly recommend giving this a try, it almost feels like we're giving away a trade secret. 
Try mixing ProChroma pigment dispersions in up to a 1:1 ratio with a good quality acrylic gesso for the strongest colour. For lighter shades, simply reduce the pigment to gesso ratio.