by Celeste Percy
from Threads #89, pgs. 14 and 16

At one time or another, every sewer will probably need to insert a zipper into a garment, and with a little bit of preparation, you'll be able to do it easily with great results. I'll show you how to sew in a standard zipper, using both the centered and lapped methods, as well as how to insert the popular invisible zipper that "disappears" into the garment seam. But first, here are some helpful tips regardless of the type of zipper or insertion method you choose.

Both standard and invisible zippers come in a variety of lengths. I suggest starting with a zipper that's slightly longer than the zipper opening on your garment, especially when working with a standard centered or lapped application (it's usually easier to shorten a zipper than it is to insert it precisely into a given space). For example, if your garment has a waistband, insert a longer-than-needed zipper that extends beyond the waistline seam, stitch over the zipper, and trim away the excess when you attach the waistband. You can cut a zipper at the bottom to shorten it as well; just be sure to add a new zipper stop by whipstitching over the teeth at the bottom of the zipper, then cutting it 1/2 in. to 1 in. below this new stop.

Interface the zipper area
Before inserting a zipper, it's a good idea to add a strip of interfacing along the seam allowance, especially when using a lightweight or unstable fabric, to help support the zipper's weight and stabilize the fabric. I use a strip of lightweight, fusible interfacing that's about 1 in. wide and the length of the zipper opening. Fuse the interfacing strip to the zipper-opening seam allowances, extending over the seamline about 3/8 in. For a crisp opening edge, interface only the seam allowances.

Machine-baste the zipper tape to both seam allowances, stitching through the tape and seam allowance only.		Draw a chalk guideline on the fabric 3/8 in. from the seamline and topstitch the zipper in place, starting at the bottom and stitching to the top on each side.

The centered zipper
Sew the garment seam, machine-baste the zipper opening's seam allowances together, and press the seam open. Use a two-step process for this method, machine-basting the zipper tape to the seam allow-ances first, then topstitching the zipper in place from the right side of the garment. For best results, and to avoid rippled edges, topstitch directionally from bottom to top on each side through all thicknesses. Use your machine's zipper foot, which allows you to stitch close to the zipper teeth, and remove the seamline basting stitches once the zipper is inserted.