How come ancient Egyptian ink didn't fade during thousands of years?

This ink's main ingredients were charcoal, honey and gum arabica. 


I understand charcoal is carbon and it would remain black for long time or forever just like coal. But gum arabica is organic and I would assume it would decay just like any organic material thus breaking the carbon bond and then carbon would've just turned into dust and disappear from papyrus or clay vessels, but apparently that's not the case.


