We've used a variety of substrates over the years, and kraft paper always seems to be incorporated somehow. We've been experimenting with coarse-grade aspen chips for the past 6 months, with very, very good results. Paper is laid over the aspen so our snakes can lay beneath it, and we have happy bloods & short-tails that eat, shed & breed like clockwork. They're all housed in Animal Plastics racks, in climate-controlled rooms.

HTH!

K~