From Mayer, an average starting place:
Gum arabic 2 oz
Boiling water 4 oz fl oz
Honey-water 1:1 or sugar syrup or glucose
1.25 fl oz
Glycerin 1.5 fl oz
Wetting agent 2-6 drops
(Oxgall is traditional; usually synthetic these days)
Preservative 1/4 teaspoon
(Dowicide A or 10% phenol)
Dissolve the gum in the water, then add the rest of the ingredients. You might have to fiddle with the proportions to suit your own preferences, and probably will have to fiddle a bit for individual pigments.
caters to people that like to make their own paints.