I took my Mom out shopping yesterday. She loves to go to thrift stores too. So fun! I found a package full of seam binding, great colors. I thought seam binding was always rayon but one package is marked taffeta. I have never seen that before this. Anyway, there was also a roll of this stuff! Bottom two pictures. I have no clue what it is. It feels like plastic to me. It is quite stiff. Anyone know what it is? Or what you do with it?