Gallic acid can react with ferricchloride and then appear blue-black colour. It uses in pharmaceuticals industry (such as in the synthesis of trimethoprim), food and feed industries, ink dyes, photography, and paper manufacture.

Assay	99.0%Min
Loss on drying	10.0%Max
Residue on ignition	0.1%Max
Tannic acid	1.0ppm Max
Turbidity	10ppm Max
Water solubility	Clear