Sewing an Invisible Zipper with Regular Zipper Foot
A zipper is a zipper unless it is invisible. But that is no longer the case. In fact, I now find invisible zipper easier to insert than regular zippers due to this little tutorial I am going to share. Inserting an invisible zipper used to involve a separate plastic foot that allowed for the curling of the zipper tape and the close placement of the stitches. However, this can all be accomplished with a regular zipper foot and some careful prep work.
First, unpack and layout your invisible zipper on your ironing board and unzip. Place your zipper facedown and press your iron against the zipper teeth until they begin to curl toward the front. Continue to press until your zipper tape is flat with no more curl. Press your zipper tape flat all the way down the zipper to the zipper pull. Don't worry about not being able to press the tape that is blocked by the zipper pull, that is usually hidden by the garment. You can see the difference between the flat tape and the still curled tape in the photo. The tape is pressed flat on the left and untouched, un-pressed on the right.
Next (and this is the really easy part) line up and pin and sew your zipper just like a regular zipper. "What! It can't be that simple!" you might say. Oh but it is and you can see why it is actually easier than a regular zipper because you don't need to topstitch after applying the zipper to keep the fabric out of the teeth. The curl that you ironed out comes back when you zip up your zipper and this keeps the fabric away from the teeth. The only real difference between sewing a regular zipper and an invisible zipper is that you are encouraged , Nay- required, to sew as close to the zipper as possible with an invisible zipper. With a regular zipper you must be careful not to get too close (which will make zipping tricky) and not too far away (which will make the zipper too visible). An invisible zipper is also more forgiving should your stitch line not be perfect.
I recommend always sewing your invisible zipper from the top down. If you prefer to always have your fabric on the left of the needle like I do then you might discover extra fabric or zipper at the top or some other mismatch. If you start both sides of the zipper at the top, you are in a better position to match up at the bottom.
Invisible zippers are not only more hidden from the eye but also from the drape of the clothing and from the little rub when placed under the arm (if I wear a dress too long with a regular zipper placed on the side seam, I find a raw area rubbed away at night). I find there is none or less puckering with an invisible zipper in knitwear. I also much prefer the zipper pull; a small thing I know but details are what make me proud to wear my own handmade clothes.