Dark refractory dies

[sirmais]

Hi guys!

I have a problem. Why my refractory dies looks dark like this after firing? I can not figure that out.

I use GC LiSi PressVest, Zhermack silicone, printed model and dies.

Thanks a lot!

 

[Gigieiya]

I would try to raise the temperature and holding time. Had the same problem with LiSi with only difference that the lab i worked in had no burnout oven, so i had to preheat dies with open flame and then dropped them to porcelain oven After additional burning on the 2d try i succeed. My friends suggesting Norivest...

 

[Affinity]

Either underfired or contamination from the oven.