Do you know when this was promulgated? There are some old (ca 1960's) treatment guidelines that have been superceded. To the best of my knowledge, the only guidelines on textiles formally approved by the Smithsonian textile conservators appear on the SCMRE website http://www.si.edu/scmre These do not specify treatment protocols. Sincerely, Mary Ballard Senior Textiles Conservator, SCMREjkip@xxxxxxxxx 04/30/03 08:26AM >>>There is a purportedstatement made by the Smithsonian Institute which says it now *requires* that polyester thread be used in repairs made on quilts in their collections. They found that it was the thread, not the fabric, that was coming apart after 100 or so years. Tests were done on identical cotton fabric/cotton batting pieces that were quilted with poly or cotton thread. The samples were then subjected to numerous washings, light exposure, etc., to simulate aging. The final result was that the fabric was not damaged by the poly thread, and the poly thread did not break, while in some cases the cotton thread did break. Is there any documentation on this? Is there a certain brand recommended and if so, is this all poly or poly/cotton blend? It is my understanding quilting books reccomend that cotton thread be slighting weaker than fabric so as not to cause stress. Would appreciate any help and additional information.