Conversion Cotaing Chemicals

zinchromate 161 and 161 spl

blue chromate conversion processes

these  are blue passivating formulations specially  developed  tproduce  a  clear bluish bright chrome like  chromate  conversion coating on zinc plated components. By simple immersion 161 or 161 spl  provide a very attractive uniform blue colour coating  which protects zinc from finger staining, discoloration and  corrosion. They  are  characterized  by  low  concentration,  low  cost,  no leaching  deep  is required and very simple  in  preparation  and operation.Zinchromate 161 is a low cost passivating salt and used considerably  in all applications.While zinchromate 161 spl is  a specially  formulated passivating salt for getting highly  bluish

bright chrome like chromate conversion coating .

Solution composition and operation :

zinchromate 161 or 161 spl           gm/lit.        4.0

nitric acid (54 %)                                  gm/lit.      12.0-15.0

temperature                                         room

ph                                                               0.5-1.2

time                                                           second         5-30

preparation :

dissolve the required quantity of zinchromate  161 or 161 spl  in clean water and add with care the required amount of concentrated nitric acid (54 %) with stirring. Add water to make up the  final volume.


for  this solution pvc or polythene containers or pvc lined  m.S tank can be used.

Process sequence:

1.    Bright zinc plate (6-8 microns thick )

2.    Swill thoroughly in cold water (twice)

3.    Bright blue passivisation in zinchromate 161 or 161 spl.

4.    Water swill

5.    Water swill and dry

maintenance of the solution

if  the solution is worked continously,an occasional addition  of conc.  Nitric acid 2 ml/lit. And 0.5 gm/lit of zinchromate 161 or161 spl.  Will be beneficial. However when bath  solution  spent, it can be discarded and a fresh solution can be prepared. Roughly 1000 to 1250 sq.Ft.Of zinc plated components are passivated by  1 kg of zinchromate 161 or 161 spl.

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