Having looked at various ones, I'm leaning towards muslin, but I have no experience of the fabric (I wear modern acrylic), and due to The Situation I can't wander into a department store and handle some.
Is it slippery, like silk? Soft? Itchy? Thin fluttery layers? Does it bunch up and crumple a lot in normal use? What happens if you spill tea on it?
I'm looking to write quite comically about someone wearing a fancy frock who has 0 experience of wearing fancy frocks.