The only thing I won't use is old thread. My mother gave me a whole box of thread that must have been 40 years old. I tried piecing with it and the thread kept breaking....very aggravating...when I mentioned it to a quilting friend she told me that old thread loses it's flexibility so the strenght has been compromised and it breaks easily...you don't want that attempting to hold together your quilt....so if you know it's more than 30 or 40 years old....I say toss it.