The POA had the recycle folks out to speak at a meeting a year or so ago.
http://www.poa4us.org/bulletins_file...etin201601.pdf (page 9)
There was a good recounting of what they said in the January '16 newsletter. I was surprised to learn that paper run through a shredder is also not accepted. They use some sort of wind sorter to separate materials, and the shredded paper is too light.