Remove the stage curtain from its hangers and search the entire curtain for tears or loose seams. It is easier to repair all parts of the curtain at once, rather than perform multiple repairs.
Apply iron-on tape to any tears. Follow specific product instructions, as different types of tape require different temperatures and application. Extend the patch at least 1 inch in all directions surrounding the tear. This prevents the damage from spreading.
Sew all edges of the iron-on tape to the curtain with a thick, strong thread using an overcast stitch. Keep the stitches as close together as possible, and continue until all edges are sealed.