Kevlar thread can be used to finish ends of flat wick so they do not fray. Thicker 1/16 inch twisted cord can be a better option for many applications, as it is more durable than thread. If you do use thread to finsh the edges of flat wick, knot each stich so that if any of the thread burns though it will not unravel the whole seam.
For more information about Kevlar Fire Wick click on the link below.
Diameter .013 inch (.034mm)
Length 65 feet (20 meters)