Measure the width of the window that is receiving the treatment and multiply it by three.
Cut a piece of fabric that is as wide as the measurement you found in step 1 and between 2 and 4 feet wide. A wide window scarf gives you a thicker drape.
Turn on an iron, heating it to the lowest setting.
Cut four lengths of iron-on hem tape, each as long as one side of your fabric rectangle.
Fold a length of iron-on hem tape into the edge of the corresponding side of the fabric, sandwiching the tape between two layers of fabric.
Press the fold using the warm iron, holding the iron in place for 5 seconds before moving on to the next segment. This seals the length of iron-on hem tape to the fabric, creating a finished edge. Continue until one entire side is finished.
Repeat steps 5 and 6 for the other three sides, finishing all the edges. At this point, the window scarf is ready to be draped or hung from your curtain rod.