So I did my first Lisi press. Two separate molars A1 and A2 .. I used MT pellets for both. Press temp of 915c. and a 15 minute hold. Both crowns look as though were pressed out of a gray enamel pellet to me. No dentin coloring at all. Also, big demarcation line that looks like a crack.. Any thoughts on where I went wrong with the firing ? Thanks..