Dyeing of cotton with indigo using iron(II) salt complexes

The use of gluconic acid as a ligand for complexing iron(II) salts and for vat dyeing of cotton has been reported previously. The present paper reports the observations on the use of iron(II) salts complexed with such ligands as tartaric acid and citric acid for the reduction of indigo at room temperature and subsequent cotton dyeing. This study includes the measurement of reduction potentials of various iron complexes their effect on dye uptake and the deposition of iron on dyed fabric.