A short technical article reporting experiments on the vat dyeing behavior of Indanthren colors, extending earlier work on Indanthren Blue to Yellow GK, Brown R and Orange RRTS. Graphs show how dyebath exhaustion and hydrosulphite content change over time and with temperature, caustic soda quantity and vat concentration. The authors also give figures for hydrosulphite loss by oxidation and the caustic soda it consumes, with advice for jigger dyeing.