this invention describes a method of treating zinc die - cast articles to produce an adherent coating suitable for the application of subsequent electroplated metallic coatings without the use of solutions containing cyanide ions . the method of the invention generally includes the steps of : ( a ) optionally , but preferably , cleaning and activating the zinc die - cast article ; ( b ) electroplating the article in a bath comprising zinc ions , alloying metal ions ( which are preferably nickel ions ), and counter ions ; ( c ) subsequently coating the article by electrolytic or electroless means with further metallic layers and optionally a final organic coating . the cleaning and activating step is preferred to provide a surface that is suitable for electroplating . defects such as lack of adhesion , porosity , roughness , dark spots and non - uniform coating are likely to occur on poorly prepared parts . the surface preparation process also serves to activate the surface of the part so that it is optimally receptive to the deposition of the metal coating . the zinc die - cast articles are first cleaned in a neutral or alkaline degreasing cleaner to remove oils from the surface of the articles and also any residual buffing compound that may be present from post - casting buffing operations . the articles are thoroughly rinsed and then activated to remove surface oxides by a short immersion in a weakly acid solution such as 5 - 10 % sulphuric acid . thorough rinsing is preferred between all cleaning stages and also prior to electroplating to remove all traces of acid and alkali from any porous areas on the article . after cleaning and activating , the zinc die - cast article is electroplated by making it the cathode in an aqueous solution containing zinc ions , alloying metal ions , which are preferably nickel ions , and counter ions . the source of zinc and alloying ions in the invention are any water soluble zinc or alloying metal salts . of particular preference for zinc are zinc chloride , zinc sulphate , zinc acetate and alkali metal zincates . the preferred source of the alloying ions is the chloride , sulphate or acetate salt of the chosen alloying metal , preferably nickel . the concentration of zinc ions in the electrolyte is generally between 2 and 100 g / l , and the concentration of alloying metal is generally between 0 . 2 and 100 g / l . the counter ions merely refers to the anions ( eg . chloride , sulfate , acetate , etc .) that are associated with the metal ions in the salt chosen . other useful alloying metals include cobalt , copper and iron . in addition to the zinc and alloying metal salts the solution may contain other salts and additives , for example ( i ) sources of hydrogen ion or hydroxide ion to adjust the ph of the electrolyte , ( ii ) buffering compounds such as ammonium ions , borate ions or organic acid species , ( iii ) complexing agents such as an amine to prevent precipitation of metal hydroxides , ( iv ) additional inorganic salts to improve the conductivity of the electrolyte , and ( v ) wetting agents and brightening agents . in a first embodiment of the invention , the electrolyte is composed of a water soluble zinc salt providing zinc ions preferably in the concentration range of 10 - 100 g / l , a water soluble alloying metal salt providing alloying metal ions preferably in the concentration range of 10 - 100 g / l , a buffering compound and optionally further inorganic salts , wetting agents and brighteners . preferably the zinc salt is zinc chloride , the alloying metal salt is most preferably nickel chloride or nickel sulphate , and ammonium chloride or boric acid are the preferred buffering agent . the electrolyte is operated at a mildly acidic ph in the range 4 . 5 - 7 . 0 , preferably about 5 . 0 - 5 . 5 , and can be operated in the temperature range of 10 - 90 ° c . but preferably at 20 - 30 ° c . in a second embodiment of the invention , the electrolyte is composed of an alkali metal zincate providing zinc ions preferably in the concentration range of 2 - 30 g / l , a water soluble alloying metal salt providing alloying metal ions preferably in the concentration range of 0 . 2 - 5 g / l , an amine compound to act as a chelating agent for the alloying metal ions , an alkali metal hydroxide , optionally an alkali metal carbonate and optionally wetting and brightening agents . preferably the alkali metal zincate is sodium or potassium zincate , the alloy metal salt is nickel sulphate , the chelating agent is a polymeric amine or a substituted ethylenediamine compound and the alkali metal hydroxide is sodium or potassium hydroxide . the electroplating solution is operated at a ph of between 10 and 14 and can be operated in the temperature range of 10 - 90 ° c . but preferably at 20 - 30 ° c . both embodiments of the invention provide a zinc alloy deposit which normally consists of 70 - 90 % zinc and 10 - 30 % of alloying metal , preferably nickel . the anode in the electroplating baths may be either metallic zinc , the alloying metal which is preferably nickel , or insoluble anodes for example titanium coated with mixed metal oxides . for the first embodiment of the invention a zinc anode is preferred , and for the second embodiment of the invention an anode of the alloying metal , which is most preferably nickel , or a coated titanium anode is preferred . the articles are electroplated in the solutions of the invention at current densities of between 0 . 1 and 5 . 0 a / dm2 , preferably between 1 and 4 a / dm2 , and the plating time is normally 2 - 10 minutes , preferably 4 - 8 minutes . under these conditions an adherent zinc alloy , preferably a zinc - nickel alloy , is deposited . typically the deposit contains 10 - 30 % of alloying metal with the remainder being zinc . both embodiments of the invention have minimal or no attack on the zinc die - cast articles and provide for deposits with excellent coverage into the recesses of complex - shaped parts , thereby providing optimum protection during subsequent processing stages . although both embodiments of the invention can produce the desired coating , the preferred embodiment is the mildly acidic bath described in the first embodiment . after electroplating in the bath of the invention the articles are subsequently electroplated with any suitable electroplating bath , however due to the coating of the invention being 70 - 90 % zinc , processing in alkaline baths is preferred with pyrophosphate copper being most preferred . for optimum adhesion of the pyrophosphate copper deposit to the coating of the invention , it is preferred to apply a voltage to the article before immersion in the copper pyrophosphate bath . in the following examples , unless specified differently , all zinc die - cast parts have been treated according to the following procedure ; activator ( 25 g / l sodium bisulphate and 2 g / l sodium fluoride , room temperature , 30 seconds ) electroplate in alkaline copper ( ii ) pyrophosphate bath ( 3 a / dm2 , 20 minutes ) electroplate in conventional watts bright nickel bath ( 4 a / dm2 , 13 minutes ) assess the deposit for blistering and other indicators of poor adhesion a zinc die - cast part was pretreated and then electroplated in a conventional alkaline cyanide copper ( i ) electroplating bath at 1 a / dm2 for 5 minutes at a temperature of 55 ° c . this example is representative of the conventional established process of the prior art . a zinc die - cast part was pretreated and then electroplated in the solution at 3 . 5 a / dm2 for 20 minutes at a temperature of 55cc followed by conventional nickel and chromium plating . a zinc die - cast part was pretreated and then electroplated in the solution for 15 minutes at 0 . 5 a / dm2 and a temperature of 55 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional nickel and chromium plating . this example is believed to be representative of the prior art of u . s . pat . no . 4 , 469 , 569 and u . s . pat . no . 4 , 521 , 282 . a zinc die - cast part was pretreated and electroplated in the solution for 15 minutes at 0 . 5 a / dm2 and a temperature of 55 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional nickel and chromium plating . this example is believed to be representative of the prior art of u . s . pat . no . 6 , 054 , 037 . a zinc die - cast part was pretreated and then immersed in the above solution for 1 minute prior to being electroplated in the solution of example 3 for 15 minutes at 0 . 5 a / dm2 and a temperature of 55 ° c ., followed by conventional nickel and chromium plating . this example is believed to be representative of the prior art of u . s . pat . no . 3 , 928 , 147 . a zinc die - cast part was pretreated and immersed in the solution . a displacement copper deposit formed immediately upon immersion into the solution . the part was electroplated in the solution for 10 minutes at 0 . 01 a / dm2 and a temperature of 30 ° c . and subsequently electroplated by conventional pyrophosphate copper , nickel and chromium plating . this example is believed to be representative of the prior art of u . s . patent application 2008 / 0156652 . a zinc die - cast part was pretreated and electroplated in the solution for 2 minutes at 2 . 0 a / dm2 and a temperature of 55 ° c . this electroplating stage was followed by conventional pyrophosphate copper , nickel and chromium plating . this example is believed to be representative of the prior art of gb2272001 . a zinc die - cast part was pretreated and immersed in the solution for 3 at a temperature of 50 ° c . an immersion nickel deposit formed . this stage was followed by conventional pyrophosphate copper , nickel and chromium plating . this example is believed to be representative of the prior art of u . s . pat . no . 6 , 827 , 834 . a zinc die - cast part was pretreated and electroplated in the solution of example 8 for 10 minutes at 1 . 0 a / dm2 and a temperature of 50 ° c . this electroplating stage was followed by conventional pyrophosphate copper , nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 5 minutes at 4 . 0 a / dm2 and a temperature of 55 ° c . and subsequently electroplated in conventional pyrophosphate copper , nickel and chromium plating . this example is believed to be representative of the prior art of u . s . patent appl . 2006 / 0096868 . a zinc die - cast part was pretreated and electroplated in the solution for 10 minutes at 2 . 0 a / dm2 and a temperature of 30 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 10 minutes at 1 . 0 a / dm2 and a temperature of 30 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 5 minutes at 2 . 0 a / dm2 and a temperature of 20 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 5 minutes at 4 . 0 a / dm2 and a temperature of 25 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 10 minutes at 1 . 0 a / dm2 and a temperature of 25 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . a zinc die - cast part was pretreated and electroplated in the solution for 5 minutes at 2 . 0 a / dm2 and a temperature of 25 ° c . a cathodic potential was applied to the part prior to immersion . this electroplating stage was followed by conventional pyrophosphate copper ( with a cathodic potential applied prior to immersion ), nickel and chromium plating . the foregoing description and examples are provided by way of illustration only . although the invention has been described with reference to particular and preferred features and embodiments it will be understood to those skilled in the art that these are not intended as limitations of the scope of the invention .