Definition
An invisible zip is a zip whose teeth are turned to the back, so once sewn into a seam only the small pull shows and the seam looks unbroken.
Invisible zips have a coil on the inside of the tape instead of teeth on the outside. Sewn close to the coil, the tape folds back and the seam closes over it, which makes them the standard closure for dresses, skirts and tops, in the center back or a side seam.
What to know:
- Buy it longer than the opening, by 2 to 5 cm (3/4 to 2 in). The pull has to sit above the end of the stitching to close fully.
- Insert it before the seam below is sewn. Sew each tape to an open edge, then close the seam beneath the zip.
- Use an invisible zip foot if you can. Its grooves hold the coil upright so the needle stitches right next to it. A regular zipper foot works too, but you must unroll the coil with your fingers as you sew.
- Press the coil flat from the back, on low heat, before you start, so it is easier to stitch close.
- Stabilize the edges with narrow strips of fusible interfacing or stay tape on lightweight or stretchy fabric, to prevent rippling.
Sewly's sewing guide lists the zip a pattern needs, with its length, among the notions. For the full method, see how to insert an invisible zip. The visible alternative is the lapped zip, and the right foot is covered under presser foot.