Interlining is a flannel-like, napped cotton material used between the face fabric and lining of a curtain. It adds body, drapability, insulation and protection to the curtains. It can be used with any fabrics to add a substantial and luxurious feel. It is especially important to interline silk fabrics to add protection from sunlight. Interlining a curtain panel adds an extra step to the sewing process but the result is a professional look. Drapery panels as well as valances benefit from interlining. These instructions use a plain drapery panel with a flat heading to show you how to accomplish this task.
Measure the distance from the bottom edge of a curtain ring to floor. Subtract 2.5 cm (1 inch). This is your finished length. Add 30 cm (12 inches) to the finished length measurement to achieve the cut length measurement. For example: 227.5 cm (91 inches) less 2.5 cm (1 inch) equals 225 cm (90 inches) plus 30 cm (12 inches) equals 255 cm (102 inches) cut length.
Cut the face fabric to the new measurement length -- 255 cm (102 inches) in the example.
Cut the lining 10 cm (4 inches) narrower and 7.5 cm (3 inches) shorter than the face fabric.
Cut the interlining the same as lining.
Lay the interlining on the wrong side of the lining. Work with the lining and interlining as if they are one piece from now on.
Turn up a 7.5 cm (3 inch) double hem on the lining/interlining. Fold up 7.5 cm (3 inches) and then fold up again to form double hem. Pin it in place. Sew through all thicknesses.
Turn up a 10 cm (4 inch) double hem on the face fabric. Pin it in place. Machine sew or hand sew the hem in place.
Lay the face fabric and linings right sides together. Align the top of hems. The lining hem should be 2.5 cm (1 inch) shorter than the face fabric hem. Pin the side edges. Sew, using a 1.3 cm (1/2 inch) seam allowance. Stop sewing at the top of the hems.
Turn the curtain right sides out. Because the linings are narrower than the face, the side edges will roll to the lining side. This forms the side hems. Press them.
Slipstitch the bottom hems at the side edges, leaving the two hems free across the width of the panel. You can mitre the hem corners for a neat look.
At the top of the panel, fold 1.3 cm (1/2 inch) of fabric to the lining side. Press it. Fold 8.8 cm (3 1/2 inches) to the lining side, forming the flat header. Stitch this in place, sewing through all thicknesses.
Place drapery pins, clip-on rings or sew-on rings at even intervals across the header. It is normal to have seven rings per single-width panel. Hang the curtain on a rod.
To embellish a flat header panel, sew trim along the stitching line at the top of the panel. To make a cuffed panel, cut the fabric 10 cm (4 inches) longer than the cut length measurement and fold the flat header down towards the face fabric, forming a cuff. Attach rings at the fold. If you are using rings with an eyelet, drapery pins make hanging the curtain easy. Just slip the hook end through the eyelet.