Electroless nickel plating of aluminum

In a process for plating zinc or tin coated aluminum substrates with an adherent, non-blistered electroless metal coating by metal plating from a first electroless plating bath to the desired thickness, the bath being replenished as needed to maintain the desired metal concentration, and with the bath being used until the electroless metal coatings produced on the substrates are non-adherent and blistered after which the bath is discarded, the improvement whereby the lift of the bath is increased comprising:

• plating a thin coating of the metal on the substrates from a second electroless metal plating bath prior to plating to the desired thickness with the first bath, both electroless metal plating baths containing a source of metal ions and a reducing agent to reduce the metal ions.