Re melting

Hi when I re melt my runs and riders I have way more slang and tougher casting then when I use what I call first melt iron
Is that normal ...?
Thanks
Todd

 

You're casting iron? What are you using for flux?

 

Have you tried sandblasting off the sand burnt into the iron surface?.

 

You have to add some inoculant...ferrosilicon based...will soften up iron and gives it more machinability and less shrink defects.

 

I'm casting iron yes
I use no flux
And I do use ferosilicon
It only happens on the re melt
And I wire brush the sand off
Thanks
Todd