Iron-on Patches and Ultralight Fabric?

My experience with heat and synthetics has been dismal. Gluing and stitching the corners to prevent peeling worked pretty good for me. Contact cement like Barge glue or SilNet are my choices. You can SilNet the back side of the stitches to improve waterproofing.

Confirmation of a hypothesis. Thanks Dale.

It's not that simple. What is the adhesive in the iron-on fabric? If the adhesive is flexible, it might work fine. Many airmat patches go that way, and the patches are very reliable ime. I have tested some. If it is a stiff thermal adhesive, then you would have problems – but I have my doubts that any iron-on patch would go that way. Melting the fabric is controlled by the temp you set the iron to. Most irons have a dial with calibrations for that. Cheers

The best results I had with heat was using a heat gun to soften all the glue and then press it down on the pack. The problem is getting a good seal all the way to the edge. My guess is that the glue is made for smooth cotton fabric. Textured stuff like a ballistic nylon messenger bag was a fail. Pressing a hot iron down on your $$$$ synthetic backpack is scary stuff. Laundry irons are so big and there isn't much heat in the tip. Back in my old B&W photography days, we use a tacking iron to secure photo and dry mount tissue before putting in a heated dry mount press. Those tacking irons would be prefect for stuff like this. Unfortunately, a new one is $75-$100. Using SilNet, you would have a chance of removing it later– snip the stitches and peel. I got a really nice OR softshell jacket with a logo embroidered on it and covered it over this way. I've done a couple messenger bags too. Being here in Seattle, we see all kinds of nice gear with Microsoft and other techy logos stitched on. I was thinking about finding a way to embroider over the old logo, but it seems to be a downward spiral and best left alone.