Mini Tutorial: ​Sewing An Invisible Zipper Application 

1. Start by clean finishing each seam edge individually prior to aligning and the zipper. Use the clean finishing technique of your choice- in this case a serging stitch is used. Open the zipper and align the left zipper tape with the left seam edge placing it face down on the right side of the garment. Insert pins perpendicularly to keep the edges aligned.

Before you move on to machine stitching the zipper, it helps to replace the pins with a temporary hand basting stitch for increase stability and comfort during the machine stitching process. 

2. Starting at the top, insert the zipper coils into the corresponding invisible zipper foot slot and insert the needle into the crease created by the zipper tape fold. 

3. Stitch next to the zipper coils as the presser foot slot keeps the zipper coils lifted and tape unfolded throughout the process- this will ensure that the stitch is applied evenly behind the coils but not so close that it restricts the zippers functionality. 

4. Align the other zipper portion to the other seam edge and hand baste the zipper to secure. The second zipper portion should be aligned at exactly the same location along the seam as the first one. When the zipper is closed, the top and bottom horizontal seam edge should align perfectly. 

5. Repeat the stitching process, by guiding the zipper coils with the other presser foot slot. The zipper is always stitched from the top down, ending the stitch as close as you can to the zipper slider located at the bottom. 

6. Once the zipper is attached, remove all hand basting stitches with a seam ripper, and align the bottom portion of the seam as you would any regular seam: face sides touching and edges aligning. Insert pins perpendicularly trough both fabric layers, moving the bottom of the zipper tape away from the garment to encourage the seam edges to layer flatter. 

7.Starting at the bottom of the existing zipper stitch, and using a regular zipper foot (so you can stitch right next to the zipper coils), stitch the seam at the designated seam allowance. If the bottom of the seam is extra long, you should switch to a regular presser foot once you've passed a few inches form the zipper's bottom. 

8. Iron bottom of the seam with seam allowance layers open. It is easiest to iron form the wrong side of the seam. 

When, the complete invisible zipper should blend and disappear into the seam with only the zipper tap visible at the top. The transition from zipper to the rest of the seam the bottom of the zipper should be smooth and unnoticeable.