Zirconium propionate is a white powder with molecular formula Zr(CH3CH2COO)4. Its structure is complex, but is believed to be based on hydroxy-bridged zirconium polymers, with the propionate carboxyl group bonded to the zirconium. Propionates are salts or esters of propionic acid. It is not soluble in water, but dissolves in a solution of isopropanol, ethanol and ethyl acetate. When tamped or untamped, it has a density of 1.14 g/cm3 or 0.98 g/cm3 respectively. It is used to promote adhesion in solvent-based inks. Impurities of Hafnium are commonly present.