I plan to dye sub onto some 100% polyester fabric but the fabric kinda shifts and twists unless you’re super careful (even if you’re super careful)!
Ultimately the fabric will be fused onto a piece of card stock. Any reason why I can’t fuse the fabric to the card stock before dye sub? I’d use a heat-set Soft Fuse or something comparable.
Dye sub being a dance between heat and pressure, I don’t think it should affect the pressure. The card stock may play with the heat (absorbing some of it and partially blocking).
The other thing to consider is as the ink sublimates to a gas, are you going to absorb that into card stock and cause any bleeding?
Personally, I would use heat tape to tape down fabric in place and mount card stock after sublimation.
OTOH heat mounting the card stock may cause further dye diffusion and bleed/blur. Depends on the relative temperatures required.
Can the Soft Fuse withstand the 350-400 degrees needed for dye sublimation?
Most likely. It’s an iron-on product that’s intended for use primarily on cotton appliqués.
EDIT: It’s a soft stabilizer.
I’d bet it will be ok, but worth a test, first.