The fungal visor degrades over 30,000 charges of combat, and will revert into a mycelium visor web when fully degraded. A partially degraded visor can be repaired using fungal flakes - 3 per 1% - which also requires 3 Crafting and some thread, granting a scaled amount of Crafting experience. If it fully degrades, it will need to be re-created from the visor web.
The visor can be cleaned at any point to return the mycelium visor web, and half of the remaining charges in fungal flakes, rounded up - e.g. an 80% charged visor will return 120 flakes. Additionally, alchemy performed on the visor returns a scaling amount of coins based on the remaining charges.