"Don’t," Snape said sharply, his eyes narrowed as he peered closely at Harry’s skin, "Hmm, it is improved somewhat," another flick of his wand, and a mirror was in Snape’s hand, and he positioned it so Harry could see his neck reflected back at him - while some of the redness had receded and the wound was closed again, Harry felt that "somewhat’ was generous in this instance, "We must repeat the process - possibly for the next several months," Snape looked as ill as Harry felt by the prospect, "I will redress it, and you must come and see me after your first day of class," he summoned the salve he had given Harry, and held it out to him, intention clear.