Elmer's all purpose glue will hold patches without sewing. When DH was in the military, being a young wife and we were broke, he was having to change rank patches every few months. Those things then were impossible to hand sew. I used Elmer's All purpose glue when he had to have the new rank patch for the next day for a detail. Those patches stayed on through washing and drying and heavily starched ironing. I didn't know at the time that the patches had to be sewn. His never frayed to be noticeable they weren't. Thankfully he got high enough rank I could afford to have them sewn on like they should be. I don't know how the rank patches are now, I hope not as thick and hard as they use to be.