Curtain panels give your room an elegant, tied-together look. Depending on the size of your windows and your desired curtain width, you may need to sew two or more panels together. Because the back sides of curtains are seen through the front of the window, it is important to use a seam that looks finished and neat on the wrong side of the fabric. French seams work well for this task and are quick and simple to make.
Launder your curtain panels and dry them on a high setting. Iron the fabric to remove any wrinkles.
Cut off the finished edges on the long left edge of one panel and the long right edge of another. Place the two panels with the wrong sides together and pin at the long unfinished edges.
Sew the two panels together. Use a straight stitch and a ½-inch seam allowance. Remove the pins. Trim the fabric outside of the seam to 1/8 inch.
Turn the fabric so the right sides are together. Iron the long edge you sewn along the seam. Pin both layers of fabric on the sewn edge together, placing the pins every 1 to 2 inches.
Sew along this edge using a ½-inch seam allowance. This encases the raw seam in a folded seam, making both sides of the curtain neat and finished. Remove the pins. Iron the seam you made over to the right so it lays flat.
Turn the curtain over to finish the French seam. The final step in this process is sewing down the folded seam you just made so it stays flat. Line up the front side of the curtain so that the seam is underneath the right edge of your presser foot. The seam you pressed should be underneath your fabric, laying to the left.
Sew down the entire length of the seam with a straight stitch, keeping the seam parallel with the right edge of the presser foot and checking frequently to make sure the folded seam underneath the fabric is flat. Backstitch at both ends of your seam.