Drapery header tape is a stiff fabric tape. You use the tape to stiffen the top portion of drapes, also known as the header portion, to prepare the fabric for the installation of grommets. Grommets are the small circular pieces that go over the curtain rod. The header tape prevents the fabric between the grommets from sagging and allows you to more easily install the grommets in the fabric.
Lay the drapery on a flat surface with the backside facing up. Measure the width of the drapery header tape from the top edge of the drapery. Mark the spot with a pencil. For example, if you are using 4-inch header tape, measure 4 inches from the top of the drape.
Move over 12 inches and make the same measurement and marking. Continue all the way across the width of the drapery.
Measure the total width of the drapery. Cut that amount of drapery header tape from the roll using sharp scissors.
Press the header tape across the top of the fabric so the top of the tape is at the top edge and the bottom of the tape is at the markings you made.
Fold the fabric over at the markings you made. Press the entire length of the fold with your hands to make sure the tape and fabric are secure.