Black/blue,
In your case, use the Z1 the first time, then the Z5. When you are ready to apply your next coat of either Z5 or Z2, do not use Z1. The next time you use Z1 will be 6 months from now, even though you may want to put 10 coats of Z2/Z5 on before then. Make sure to use Z6 between each coat of Z2/Z5.
Aaron
