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.