You will need the following:
- a zipper opening (obviously something to put the zipper in, you know, like a skirt)
- an invisible zipper
- organza, tricot or interfacing; this is the stabilizer
- a marking pen or chalk
- a zipper foot
- an invisible zipper foot – optional. I have inserted a zipper using this method with a conventional zipper foot, so if you don’t have one of these, don’t worry, you’ll be fine.
1. Your zipper opening will need to be opened up 2 – 4 inches below the bottom of the zipper opening. If you’ve already stitched up to the zipper opening, unpick the 2 – 4 inches below the bottom of the zipper opening.
2. Cut two 1 – 2 inch strips of your stabilizer 2 inches longer than the length of your zipper. I prefer silk organza, though tricot and or a light sew-in interfacing work just fine. Baste or adhere these strips to the wrong side of your zipper opening with a 1/4 inch seam allowance along the edge.
3. You will need to mark the seam allowance for the zipper opening. I prefer to press the seam allowance for this, however, you can also thread mark or use chalk as long as the chalk has a fine tip. You want to be as accurate as possible.
4. Measure your zipper opening and mark the measurement on the zipper.
5. Open the zipper with the zipper pull below the marked measurement and with right sides together pin one open side of the zipper tape to one side of the zipper opening. Make sure the zipper coil is right one top of the seam allowance marking. Using your conventional zipper foot, machine baste the zipper tape to the zipper opening, from top to bottom. Baste 1 inch below the bottom marker measurement on the zipper.
6. Using your invisible zipper foot, or your conventional zipper foot, open the teeth with your finger and stitch from the top of the zipper to the bottom. Stitch close to the zipper teeth being careful not to catch the zipper teeth. Backstitch a few times right at the bottom marker measurement on the zipper.
7. Pin the other side of the zipper the same way as you did in step 5. Close the zipper carefully to make sure that your seams line up and that there is not a gap at the bottom of the zipper in the seam allowance. If your zipper is off, unpin and redo, until the zipper is perfectly aligned with the other side. Machine baste this side in place, with the zipper pull down below the marker measurement. Baste from top to bottom, ending 1 inch below the marker measurement on the zipper.
8. Repeat step 6 for this other side except start at the bottom of the zipper and stitch to the top. Remember to start exactly at the marker measurement on the zipper and backstitch a few times before stitching up to the top of the zipper.
9. Close the zipper. At the base of the zipper, pull up the zipper tape with your fingers and spear a pin from one stitched side to the other. I’m talking about the stitching at the bottom of the zipper, where the measurement marker is, not the basting stitches. Stitch with a conventional sewing foot from the speared pin to the end of the skirt or where the stitching of the seam below the zipper begins again.
A few things to consider:
I have tossed all I was taught about invisible zips out the window and rely on what I know works for me. I don't ever put my iron on invisible zipper coils directly and I don't press the invisible zipper coils open either. I don't do these two things for two reasons. Every time I’ve pressed open the invisible zipper teeth, the coils have been stitched into the fabric and then they rip the fabric and have a hard time zipping up or down (my sister was actually locked into a skirt that she couldn't get the zipper down from and had to seam rip her way out of it - yeah, that one takes the cake). Every time I’ve put my iron directly on the teeth coils to press out the wrinkles in the zipper, the zipper has come apart AFTER I stitched it into the garment and while I was wearing it. Yeah, just rips right in the middle of the zipper too. Rips right apart, I tell you! I’ve done this more times than I care to admit and it's happened to me while I was at work, when I could not go home and change. Believe me, there is no insurance for this kind of misfortune! If you have to press an invisible zipper, only press the tape.
A few more things. Invisible zippers have to be stabilized, in my opinion. They are so likely to warp. By that I mean that they bubble or the bottom jets out and looks really funky. Stabilize the zipper opening with the organza, tricot, or interfacing. But please, don't take my word for it - test out other versions and see what works for you. Believe me when I say you'll find your own way and then you'll be putting these in like nobody's business.
Here's a few links to some different ways to insert an invisible zipper. I recommend you read not only the tutorials, but also the comments. They are very interesting and you'll see what I mean about these being a controversial topic.
Colette Patterns - Installing an Invisible Zipper
Pattern~Scissors~Cloth - Tricks of the Trade: Installing an Invisible Zip
Grosgrain - Invisible Zipper Tutorial
May the force be with you.