Ahhh... The wonder of fusibles.
A bit of info for those that are interested:
Fusibles work best on fabric that is washed/dried without softeners or any thing else added to it. (including starch)
New fabric has finishes on it to protect it during shipping/storage. One of those finishes is a "dirt/soil repellent", which will also repel the glue of the fusible. You can often temporarily use a fusible, but it will not totally fuse to unwashed fabric. sigh.
Fabric softener includes a similar product.
When you starch/stiffen fabric with an applied product you in effect coat the fabric with the starch/sizing. When you put on the fusible it sticks to the starch not the fabric. <G> Wiping the area you will be fusing with a damp cloth removes some of the starch and allows a bit better bond.
As to the decorative stitching with rayon thread, that shouldn't make much difference. <G>
Here in the desert we have to cope with lots of drying of all sorts of stuff. I always use steam + heat + pressure when using fusibles. You do need to be a bit careful with some of them. Heat'n'Bond is very temperature sensitive, if you overheat it, it "goes away" and loses the bond completely.
I much prefer Wonder Under or Steam a Seam, or MistyFuse if I don't need the paper backing. <G>
Depends on what I am actually doing. And how many layers of fusing I will have.
Every situation is different, but if you understand the basics it all works.
Have Fun,
Pati, in Phx