Some of the materials presented here are based upon work supported by the National Science Foundation under Grant nos. 0353550 and 0752834. Any opinions, findings, conclusions, or recommendations expressed in these materials are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Research results in this report were also developed in part under a grant from the National Park Service and the National Center for Preservation Technology and Training. This report's contents are solely the responsibility of the authors and do not necessarily represent the official position or policies of the National Park Service and the National Center for Preservation Technology and Training. We are also very grateful for the very generous funding support of the University of Illinois' Research Board.