I ironed on a CGN patch to a nylon bag. I basically took these steps:
How to apply patches with heat seal backing using an iron
- Set the iron to the cotton or high heat temperature setting.
- Lay the garment down flat and place a pillow case over the area of the garment where the patch is to be attached. Place your heated iron on the pillow case and press down firmly for 10 seconds in order to heat up the area of the garment where the iron on patch is to be attached.
- Place your iron on patch on the pre-heated garment area. Then put your pillow case on top of the patch and then press down firmly with your iron for another 15 to 20 seconds.
- Remove the iron and pillow case and place the garment aside and allow it to fully cool before handling it.
I was pretty careful with the temp and timing since I didn't want the nylon to melt. For step 3 I actually applied the heat to the pillow case which was placed over the back of the nylon, with the patch bellow. It worked fine, but I haven't "field tested" it to see how well it holds up.
If you really want them to stay on through thick & thin consider sewing the patch on.