The Octopus Fluids OPAK Alcohol Ink is an opaque and fast-drying colour with an alcohol base. The Octopus Fluids OPAK series has been specially developed for use on dark surfaces. On a white or transparent painting surface you can achieve delicate pastel effects and they can also be used together with our transparent alcohol inks. In order to ensure optimum dispersion of the colour pigments, the colours must be shaken well before use.