re melting zinc problem

[SScnc]

I need some help,

I melted an ingot of Zamak 27 yesterday and it did fine, it was liquid as I expected. I turned off the smelter and it hardened overnight, now when I just remelted it, it won't go to liquid state, it's the consistency of brick mortar.

I checked it at several stages as it was heating up and it never went liquid so I left it until the crucible was red hot and it's the same.

How do I get it back to liquid for pouring ?

THANKS !

[SScnc]

WOW, 78 views and no one could tell me the zinc boiled off ?

I never knew any metal would "boil". I have to get a pyrometer set up and closely control the temp.