Patent ID: 7077975

Claim:
A method of removing Group VIII metal-containing material from a surface of a substrate, the method comprising contacting the Group VIII metal-containing material with a mixture of concentrated acids without additional added water, the mixture comprising concentrated phosphoric acid initially in an amount of at least about 10 vol-% and no greater than about 25 vol-%, concentrated sulfuric acid initially in an amount of at least about 10 vol-% and no greater than about 50 vol-%, concentrated nitric acid initially in an amount of at least about 0.25 vol-% and no greater than about 10 vol-%, and concentrated hydrochloric acid initially in an amount of at least about 25 vol-% and no greater than about 50 vol-%, wherein contacting comprises contacting the Group VIII metal-containing material with the acidic composition at a temperature of at least about 65° C.