Mixed a little over an ounce today of Z2 and the accelerator in the bottles they sent. Put two coats on and still have almost half of that left. Is this mix something I can keep on the shelf, or should it be thrown out at this point?

Also, am I using enough? I applied it sparingly and it really looks great. Finished up with some Z6 and boy that black paint POPS

 

Sounds like you are doing a great job with putting the coats on nice and thin. A 1/4 ounce should be enough to do one coat on a car the size of a Z.

Your other question has mixed answers....Zaino says to throw it out......I'm guessing due to the accelerator being used up. But some have reported keeping the extra without problems. Let us know if you find anything out.