Stealth ablative coating is a material found on UNSC stealth ships.
Black in color, stealth ablative coating serves to refract both UNSC radar and Covenant sensors, making the ship invisible to radar, similar to the way Active camouflage cloaks something from eyesight. The coating must be maintained perfectly or it will return radar signals. This necessitates constant maintenance on the entire coating. Therefore, virtually all UNSC prowlers have relatively small surface areas, so that less has to be maintained. An exception to this is the UNSC Point of No Return, which is a Prowler the size of a UNSC destroyer. Stealth ablative coating can also be found on Long Range Stealth Orbital Insertion Pods.
Strictly speaking, Ablative armor is designed to prevent damage to a ship it covers by being damaged itself through the process of ablation. A stealth ablative coating would therefore mean that once damage has been taken, its stealth features would be useless. However. If the vessel's hull was also painted beneath the armour panels, this may help to reduce if not stop it from appearing on enemy sensors.
- In reality, there are Stealth Bombers that use exactly the same technology. They achieve radar invisibility due to refractive paint, which also must be repainted every time it becomes damaged.