Al met Severus with an answering smile that brightened his face as soon as he noticed just who was approaching. He guessed the first part of Severus' words by watching his lips move, consulted the parchment at his ear for the rest.
Book-cleaning day, yes.
"The dust has been neutralized," Al confirmed, with the same flat expression he once used to suggest the neutralization of Riddle, Bellatrix Lestrange, and that one Former Administration Ministry official who dissolved their marriage. "The books should be safe to read now."