Phew it was an easy find at my fave Marrickville fabric shop. It's a linen/cotton blend, 140cm (56") wide and only $4.50m. So I snagged 6m and will wash/preshrink it tonight, and get some dye for it. I may even use dylon as iDye is harder to find.
more of a minty green than my photo (flash bleaching it out) but as i'm
dyeing it, that hardly matters. That it's a more textured weave is a
bonus, given her dress isn't in a smooth tabby weave.
Edited to add: Did a burn test before I washed it, and yes it's a linen-cotton blend. Not a paper ash residue but a minimal ash residue