I've been keeping it moist and cleaning it every 4 hours. The artist told me to keep saran wrap on it, but whenever I put it on and then clean it later there is ink residue on the plastic, is this normal? I've stopped putting the wrap on it because of this and because it falls off easily, and because its on my shoulder and I can't really put it on correctly. Also, when do I start with putting aquaphor lotion on it?