Next , the kiln 's vents would be closed and alternative tinder materials would be added to make the environment oxygen - poor and even hotter .
This process causes the entire vase to glow red , including the added paint - like clay .
The kiln 's vents would be closed and alternative tinder materials would be added to make the environment oxygen - poor and even hotter .
This process causes the entire vase to glow red , including the added paint - like clay .