I don't think the holes disappear. When I was growing up, we got flour in those, and the holes are where the heavy white thread was "sewn" to close the bag. when you pull on the right piece sticking out, it unravels and opens the sack. If I remember right, you can wash them and the holes will appear smaller but still be there. I also have some and haven't washed them. I guess I'm afraid they'll fall apart!