Carbon monoxide produced of the oxidation of the carbon of the metal spreads across the porous zones of the silicon lining where it dissociates itself depositing coal.
2C metal + O2 (air) >2 CO (gas) > C + O2
What can happen?
It does not have effect on the refractoriness of the mass. However, in old or poorly conditioned coils it can cause arches between turns.
What to do?
– Avoid overheating.
– Do not put the graphite into the empty furnace.
– Increase the density of the area by improving material quality and / or vibration.

