Abstract: A chemical composition for selectively removing an aluminum-containing material from a substrate comprises an acid having a formula of HxAF6, a precursor thereof, and a mixture of said acid and said precursor; wherein A is selected from the group consisting of Si, Ge, Ti, Zr, Al, and Ga; and x is in a range from 1 to 6, inclusive. The chemical composition can comprise at least another acid selected from the group consisting of phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydriodic acid, acetic acid, perchloric acid, phosphorous acid, phosphinic acid, alkyl sulfonic acids, mixtures thereof, and precursors thereof. The chemical composition can be used to remove aluminum seal strips selectively from the dovetail of a turbine-engine blade.