Originally Posted by
Prism99
Either interfacing or muslin would work in the short-term and mid-term. Because the blocks are vintage, I would probably opt for a thin, pre-washed muslin because it will support the blocks long-term. Fusible interfacing has more unknowns associated with it. Some might be fine, but others may eventually shred inside the sandwich and stop providing support.
I wouldn't use Pellon for that reason. There are some nice fusibles made to use with silks that are very thin and non-Pellon products. I'd use one of those.