What would you call the hard layer that forms over a wound after a severe burn?

The term used for the hard layer that forms over a wound after a severe burn is eschar. This is a thick, dead tissue that develops during the healing process, serving as a protective barrier over the wound. Eschar is typically necrotic and can be a result of tissue damage from the burn itself. It is an important aspect of the healing process as it can help to prevent infection while the underlying tissue begins to heal.

In contrast, a scab is a crust that forms over a wound when blood and other fluids have dried, typically seen in less severe injuries. A scar is the fibrous tissue that replaces normal skin after the wound has healed, signifying past injury. Crust, while somewhat similar to a scab, is often used interchangeably in some contexts, but it typically refers to any dried secretion that forms over a surface, not specifically relating to a severe burn. Thus, eschar is the most accurate term for the context of severe burn healing.