Parents in my troop have started bringing me uniforms that need help. I only sew on patches, so this is my first exposure to the seedy underside of uniforms and learning to remove glue and iron-on residue. There have been a few posts recently where I offered tips, but I thought I'd go ahead and make a fresh post so I could link back to it if needed.
The uniforms I've had brought to me recently had a combination of iron-on, fabric glue, hot glue, super glue, and stitching. Friends don't let friends sew things on with straight stitches on the shortest stitch length, people! Some with up to 3 of these things all on the same patch. And as I discovered after getting some of the patches most of the way off, some of the patches had been melted. Yay.
Don't forget to remove all the pins before starting any cleaning effort...
Here's a vest I just worked on. I didn't think to take a picture right after I finally got all of those patches off, so the middle pic is what remained after a massive cleaning effort.
To get the big chunks of hot glue off, it depends on how much they're integrated in the weave of the fabric. Some of it just pops off if you tug gently. Some of it is more stubborn if it has gotten down into the fabric fibers. For those, I warmed the vest from the back using a hair dryer so that I wasn't making it worse and pressing it in with the iron. Do not get it hot enough that it's fully melting the glue. Just a little bit warm so it wants to release. Carefully, pick at the edges with your fingernails or the non-serated edge of a butter knife. That will get most of it off. If the pieces are small, you can also try tweezers.
Let the vest fully cool before moving on to the next step.
At this point, I moved on to Goo Gone (also known as Goof Off or Dissolve It). I sprayed that directly onto all of the remaining adhesive while the vest was dry until each section of remaining adhesive was fully saturated with it. Then I let it sit for a few minutes. (I haven't had it discolor anything yet, but use at your own risk.)
My next step was to turn on a trickle of hot water (just cool enough not to burn me, but still very hot) and use a new firm-ish toothbrush to start scrubbing at the remaining glue from the outside of the vest. Don't pour the water right on the vest or it starts rinsing out the Goo Gone. Just use the wet toothbrush on each badge area one at a time while trying various directions. (Little circles, vertical strokes, horizontal strokes, etc.) You want that toothbrush to be attacking the fibers from every direction to work out as much of the adhesive as possible. I wasn't pushing hard, but I was pretty firm. Again, it didn't damage the vest, but your mileage may vary. As stuff starts releasing, grab it with fingernails or tweezers and peel off as much as you can.
Once you're convinced that the Goo Gone isn't going to remove anything else, it's time to start with Dawn dish soap. I did this just to get the smell of Goo Gone out at first, but I discovered that it was helping remove some of the thinner remaining adhesive as well. Bonus! I ended up soaking the entire vest in hot water and Dawn (original blue stuff, not any of the fancy ultra concentrated stuff) for maybe 10 minutes, then repeated the toothbrush scrubs on the most stubborn of the remaining adhesive.
I rinsed it really well and determined that it wasn't going to get any better at that point and ran it through my laundry washer on normal settings and hung it up to dry. Now it doesn't smell like Dawn or Goo Gone. Yay! That's the stage it was at in that center picture. Most of the stuff that's still on that vest is actual badge residue where they got really overheated or outright melted.
When I did all of these steps on a Brownie sash last month, it all came out and the sash looked brand new. The vest was sooo much better than it was, but still had some spots left. But now they're soft spots and with creative layering of the badges that needed to go back on, none of the old residue was still visible.