I've made many rice bags and have no problem with rice whole rice only. - the one I use now must be at least 10 or so years old. when I make mine I always use two layers of fabric, all cotton. The inside layer is a 200 count cotton. It is heavy enough to make sure not even the smallest of grain works it's way through. The outer layer is decorative cotton. I also use a cord so that the bag can be hung when not in use. This insures that it dries out and stays dry -- that is key to keep any bacteria or mold at bay.