Freezer burn

Freezer Burn, as it is known throughout the UNSC and its colonies, is an injury caused from cryopreservation in the cryo-chambers of UNSC ships and locals.

During the freezing and resuscitation process, cloth or other materials, bandages for example, next to or against the skin causes cellular damage. This results in large welts or rashes on the covered areas, described as a making the skin "blistered and raw". Most UNSC personnel are stored in cryo either naked to avoid freezer burn, or clothed and willing to endure the various injuries. It's likely that such injuries are very easy to treat, especially given the level of medical technology in the 26th century.

Spartans can be stored in cryo-preservation fully clad in MJOLNIR armor without the effects dulling their combat performance, as they are trained to dispel pain. Since their regenerative capabilities are somewhat beyond a normal human's, it's possible that they heal even faster than a normal human would.

Trivia

 * In Halo: The Flood, it is stated that John-117 had freezer burn when exiting The Pillar of Autumn's cryo pod, while in Halo: Combat Evolved it is stated that he had "no signs of freezer burn".
 * In Halo Wars and Halo Legends, characters are depicted as going to cryo-chambers fully clothed despite the risk of freezer burn. This may, however, be a liberty taken due to the developers not wanting to implement nude scenes.