Sewing with knits

[macabre-grrl.livejournal.com]

I am going to be making a long tube dress for myself out of stretch velvet or some other stretchy fabric. It is going to have slits on the sides. I am concerned about the edges of the fabric having a lot of curl in them and was wondering if anyone had any ideas about preventing this. I have looked in a few books already and it never gets addressed.

Hints?