We're looking for alternative etching compounds to chemically clean our aluminum prior to welding.  We're currently using a procedure that employs PASA JELL 101 to etch the material.  PASA JELL 101 contains a mixture of phospohoric acid (55%), nitric acid (30%), inorganic oxide (10%), and hydrofluorosilicic acid (less than 5%). 

We've used this material for a little while, but it seems to have varying degrees of effectiveness.  We're looking for some other possible etchants that have been used in the aerospace or other aluminum manufacturing industries that is somewhat aggressive and has a good track record.  Any suggestions would be greatly appreciated.

Thanks.