Normally, Chris would have looked at Smith sharply for saying that, would have asked question after question, digging until he got some sort of explanation. Like the glass you use? What do you mean? It as the same feel? Or do you use broken glass? Salvaged glass? Instead, he just looked at the smudges on his fingertips, then down at the other man and shook his head. "The residue remains, no matter the age. I've a theory on that, but I'm too tired to bother getting it right at the moment."