are they made of that old, heavy double knit stuff from the 70's? or the lighter weight poly blends? if they're made out of the old stuff, i worked with that and good luck.
http://www.quiltingboard.com/t-22163-1.htm
btw, i finished them in the years indicated, but they hung around all the years in between after my kids cut the 1/2 squares. at ten for 1 cent.