Patent ID: 7138342

Claim:
A process for combined chemically cleaning and etching parts made of aluminum and/or aluminum alloys comprising: (a) providing a cleaning and etching solution comprising: (1) 5–35 grams/liter of phosphoric acid; (2) 5–35 grams/liter of hydrogen fluoride; (3) 55–95 grains/liter of sulfamic acid; (4) 55–95 grams/liter of glycol ether; and (5) balance water; (b) contacting said parts with said solution for a time sufficient to achieve the desired amount of cleaning and etching; (c) periodically measuring the etching rate of said solution to determine if the etching rate is at or above the required minimum rate; (d) when the etching rate is below the required minimum rate, adding sufficient hydrogen fluoride to restore the etching rate above the required minimum rate; and (e) periodically adding sufficient sulfamic acid to prevent the formation of scale made of hydrated aluminum fluoride.