When stacking coated prints what kind of interleaving paper should I use?

The best way to protect coated prints when stacking or sending out to ship would be to wrap the print in Glassine paper.  You do not want to separate your prints with paper that contains acid in it.  If acid comes into contact with your print it may cause the print to turn yellow.  You can find many different types of Glassine papers online, or at your nearest art supply store.  The main thing to keep in mind when looking for this type of paper is to make sure the paper has a neutral pH level, or acid free.