Bound Invisible Zipper in a French Seam
Scroll to the bottom for the full-length video!
While developing the construction for the Willow Skirt, we knew we wanted a zipper finish that didn’t require serging or zig zag stitching — so we landed on an invisible zipper set into a French seam, with bound edges along the zipper tape. This may look like a technique reserved for advanced sewists, but take it one step at a time and you'll find it's surprisingly achievable. Our Willow Skirt testers found: they were genuinely surprised they could pull it off. With the right guidance and the steps broken down clearly, this technique is more approachable than it looks. In this tutorial, you’ll learn every step exactly as it appears in the Willow Skirt instructions, so you can follow along whether you're sewing the pattern or just here for the technique.
Why bound edges instead of serging or zig zag
Serging is fast — but it's not always the look you want for your finished garment. When you're working with French seams, the goal is a completely enclosed, raw-edge-free interior, and serging the zipper seam allowance works against that. Binding the zipper seam allowance gives you a flat, clean finish that's consistent with the rest of the seam, no serger required. It's the same approach used in high-end ready-to-wear — and once you see the difference, you might not go back.
Getting Started
This zipper and seam construction can be used on any pattern that uses an invisible zipper. We demonstrate the steps based on the pattern having 1/2” seam allowance along the waistline and side (or back) seam. The zipper opening is 7”. All of the dimensions for the pieces involved can be adjusted to your specific project needs.
What you need: Tools & Supplies
-Interfacing: This is optional and depends on the weight and weave of your fabric. Use interfacing along the seam allowance if the zipper opening needs more stability.
-Invisible zipper: Choose a zipper longer than your zipper opening so the pull can be moved below the opening while stitching. There are a couple ways to approach the length:
No trimming: use a zipper 1" longer than the opening and keep the zipper stop intact.
Trim to fit: you may have a zipper in your stash, but it is much too long. We demonstrate how to trim it to fit the opening and how to finish the cut end neatly. Use an invisible zipper that is 1”-2” longer that the opening.
-Binding: use a lightweight woven fabric cut on the straight of grain.
-1 5/8” x 1 5/8” square piece of lightweight woven fabric (most likely the same fabric used for the binding).
-Pins or clips
-Washable marking tool
-Seam ripper
-Invisible zipper machine foot and/or narrow machine foot: Depending on your machine, you may only need one of these. If your invisible zipper foot can also stitch around the bulky zipper pull, it will work for both steps — no need for a second foot.
The Steps
Follow along to the written instructions and images or scroll to the bottom for the full-length video.
Begin the French seam
Mark the bottom of the zipper opening with your preferred washable marking tool.
With wrong sides together, begin stitching from hem line toward the bottom of the zipper opening, with 1/4” SA.
When you’re about 3/4” away from the bottom of the zipper opening, stop with the needle still in the fabric layers and decrease the stitch length slightly. This will help to create a really strong stitch line at an area that takes on a lot of stress.
Continue stitching and curve the stitch line ending where you marked at the bottom of the zipper opening.
Clip and release the zipper seam allowance
Clip into the seam allowance, releasing it for the installation of the zipper. Being careful to not clip through the stitch line.
Trim seam allowance for French seam
Trim half of the width of the seam allowance (in this case it will be 1/8”).
The raw edges along this area have a tendency to poke out when the French seam is finished if they are not trimmed really close.
Press the seam flat, then bring right sides together and push the seam out as much as possible.
Finish French seam and baste zipper opening in one stitch line
Change the stitch length the longest stitch length on your machine (also known as a basting stitch).
Stitch the length of the zipper opening with that long stitch, using 1/2” seam allowance.
Stop with the needle in the fabric layers when you reach the bottom of the zipper opening.
Change the stitch length back to a standard length and continue stitching the remainder of the seam line. Now you’ll find yourself stitching with 1/4” seam allowance, since we’ve already completed the first couple steps of the French seam.
Press the seam flat and the seam allowance of the zipper opening open. The seam allowance of the French seam can be pressed toward one side, whichever side you prefer.
Prep the zipper and change the machine foot
One helpful tip is to press the teeth of the zipper away from the tape before you get going. This will offer a little assistance with getting close to the teeth as you are stitching.
Switch to narrow zipper foot. Use any foot that will allow you to easily stitch around the bulky zipper pull as you’re basting.
Baste the zipper to the seam allowance
Line up the right side of the zipper with the basted seam line on the wrong side of the zipper opening.
Baste stitch the zipper to the seam allowance. This step is securing the zipper in the exact position you want it to be in.
Open the basted stitch line along the zipper opening with a seam ripper.
Stitch the zipper in its permanent position with the binding
Bring the zipper pull down and beyond the bottom of the opening. Now the bulky zipper pull is below the bottom of the opening and out of the way for the next steps.
Switch to an invisible zipper machine foot, if different than the one used to baste the last stitch line. Change stitch length back to a standard length.
The binding pieces (qty 2) is cut on the straight grain and not on the bias. It measures 1” longer than the zipper opening. So, it this case it is 8 1/2” long and 1 1/2” wide.
Line up the right sides of the binding to the wrong sides of the zipper opening. The binding will be longer than the opening.
Begin stitching through all of the layers. The binding will be on the bottom layer.
The stitch line will need to be as close to the zipper teeth without stitching into them or over them.
Since the zipper has already been basted in place, this step is about putting the permanent stitch line in for the zipper and also attaching the binding. As you get down to the bottom of the zipper opening you’ll notice the zipper pull and the end of the binding is below the opening.
Stop the stitch line right at the bottom of the zipper opening.
Pull the zipper pull back up to the top and verify that the zipper functions properly.
Bind the zipper edges
Change the machine foot back to a standard foot.
Press the seam along the binding and then press the raw edge in to meet the edge of the zipper tape. Then press in one more time, covering the edge of the zipper tape.
Make sure that the folded edge of the binding doesn’t come so close to the zipper teeth and cause an obstruction while zipping and unzipping.
Slide the zipper pull below the bottom of the zipper opening to keep it out of the way during the next step.
Topstitch the binding down along the zipper teeth, about 1/16” from folded edge.
Repeat on opposite side.
The top edge of the binding will meet the top edge of the waist line SA, which will be hidden in a waistband most likely.
The binding will extend past the bottom of the opening.
Trim the ends of the bound zipper
Trim the ends of the binding to match the ends of the zipper tape, making them flush with one another.
At this point you can trim as much as you like, up until the zipper opening, but be sure to leave enough length to attach another piece of fabric that will cover these raw edges. I recommend reading until the end for reference.
Cover the ends of the trimmed zipper
There is more than one way to cover the ends of this tape, but this is how we do it.
Use a square piece of the same fabric used for the binding that measures 1 5/8” x 1 5/8”.
Press it in half.
Line up the raw edges of the folded square with the raw ends of the zipper tape and center it.
Stitch through all the layers with 1/4” seam allowance.
Press away from zipper and then press the sides in toward the center.
Topstitch through all layers.
Optional: Secure the end of the zipper to seam allowance
This final step is optional and will depend on if you want to have either a short line of topstitching or a back tacking visible on the right side of the garment. The zipper end is longer than the opening and it’s a nice final touch to secure it down to the seam, while also hiding this transition point from zipper opening to French seam.
Stitch or back tack through the layers directly below the zipper opening with right sides facing you. This also adds a little stability to the opening at a point that can take on a lot of stress.
