After many years of tying poop bags, we suggest tying the bag like a balloon (not a shoe with two laces). After you have got 'the business' inside & at the bottom of your dog poop bag, run your fingers up the outside of the bag to push any air out & grab it about halfway up. Now tie the top part into a knot like a balloon, and then you have it, an odour-free dog poop bag.