I have some pretty old and I'm still using it. If it would break easy or shred, I'd chunk it. I think in most cases, it's been stored indoors, and is good for a very long time. My neighbor retired years ago from a suit factory, and she has containers full of paper bobbins loaded with gray, brown, beige thread, and she gave me a bunch of it, I use it for hand sewing hexies, it's thin, but very strong, can't break it.