Iron-on for Puffy Coat

I'd be wary of ironing traditional "down-coat" fabric (it might burn or melt more readily than cotton). But you could place your appliques w/ a touch of fabric glue and then whip-stitch the edges to keep them in place.

I would never dare try iron ons with this type of jacket.
It doesn't take much to sew appliques.
Just whip stitch by hand around the edges.

I used to work at a screenprinting shop, I would think that that would be your best bet. I know that its risky because if your iron in too hot or if the iron is on the material for even a second to long, it will melt it.

I wouldn't even attempt iron-on appliques on this type of fabric, it will melt. Sew-on ones would work, and you should be able to find a dry cleaner's with a seamstress who can sew them on for you, my sister has them do my nephew's Scout badges.

I put an iron-on on my son's coat and it worked just fine. You have to place a towel between the iron-on and iron and you need a pretty solid, heat resistant surface. I used slow and steady heat and eventually it adhered. Since the fabric of the puffy coat is slippery you must hold everything very steady so it doesn't slide around. It does work, I have proof! I needed to cover a tear in the coat so I used an iron-on to hide the tear :)