Thangles are paper.

I will have to remember using spray starch, or sizing maybe, when doing triangles. I just finished a small quilt, 16x20, & some of the edges are bias, so not laying real flat & smooth. Tried to do HSTs, as much as possible, but couldn't in some spots. Oh well, we learn with each project, don't we....

I avoid bias edges as much as humanly possible. I would probably change the entire design and layout of a pattern to avoid them. lol.