We currently produce synthetic azo dyes via the so-called 'grind method'.
These dyes are converted to lake pigments for watercolor themes.
The dye is dissolved in distilled water and aq. soda wash ( sodium carbonate) added to alkaline PH.
To the solution is added aq. alum and well stirred. it is left overnight at 20 deg C. It is filtered and the light blue dye filtrate can be combined with other dye filtrates and re-treated to make more lake pigment. The dye (above) is allowed to dry and then it will be mulled and blended with Aquazol binder to make translucent watercolor paints.