Some fabrics fray nicely and look cool, like denim or cotton. Other fabrics just make a really big mess with lots of threads going all over the place.
I wanted to use some scrappy pieces in the skirt of the dress I am working on without all the mess, so I tried melting the edges with a candle.
Turned out OK, a bit blacker in places than I wanted but I can live with that. I also managed to get a few corners dipped in wax, (whoops) will add to the texture!
WARNING: Doing this with polyester and nylon makes nasty fumes, so do it outside or with lots of ventilation. Also be very careful with your fingers, candles burn and so can freshly melted fabric! Ouch!