"Good," Snape murmured, "It's not as far along as I thought." Not as far along as it should be, given the amount of time that's passed.
He drew a pot of greenish gel from his pocket and started to smooth it over any visible marks. As he worked, he started to chant under his breath. Or sing, really: there was a slow, deep music running through the Latin words. Tingling warmth spread from the salve, and when the sensation faded it left clean, unwounded skin behind.