Tissue Lame' is - or at least *WAS* the fabric of choice for half circles (or 3/4 circles) for Double Veil - especially for beginners. I'm teaching DV to somebody who I'd much rather have use Lame' to start with. Silk can come later.
Used to be just about "everybody" sold Lame' half circles, now nobody seems to. I did find the debbie's craft room - obscenely expensive but about the only source I've found too. As I'm also teaching this gal how to run her sewing machine...