Eucalyptus oil.
1. Place a little bit on a tissue and rub a dub dub on the inside of the sleeve until evil ink gone.
2. Dry with fresh new tissue.
3. If able - allow to dry for a little while - ie a piece of your 2 year old's lego jammed into the sleeve will keep it open to dry.
4. Face north and pay hommage to the god of eucalyptus