There is one class of zinc nickel coating denned as follows :
- ASTM B841 Class 1 - Deposits having a minimum of 5 and maxi- mum 12
mass % nickel, the balance being zinc, There are five chromate
conversion coating types that are defned as follows:
- ASTM B841 Type A With colorless (blue bright) conversion coatings,
- ASTM B841 Type B With yellow iridescent conversion coatings,
- ASTM B841 Type C With bronze conversion coatings,
- ASTM B841 Type D - With black chromate conversion coatings, and
- ASTM B841 Type E- Any of the above plus organic topcoat
There are three grades according to thickness and are defined as
follows:
