How To Sew A Fly Front Zipper Application
First off, it is important to understand and identify all fly application components and corresponding patterns. A fly- front zipper application requires a fly shield and a fly facing. While some pattern sets provide separate patterns for the shield and facing, a single pattern can be used to cut both compartments. This pattern can be drafted from the garment pattern housing the fly as shown in the shorts pattern pictured above.
1. Using the same pattern, cut 1 piece for the facing, and two pieces (mirror image of each other) for the fly shield compartment. You should also use the same pattern, of the facing piece, to cut an additional piece of interfacing to back the facing layer.
2. Let's start with the fly shield: Place the two pieces on top of each other with fabric face sides touching and all edges aligning and insert pins perpendicular to the curved outer edge. Stitch the curved outer edges at the designated seam allowance - 1/4" in this case. Remove each pin as you approach it.
3. To eliminate tension and allow the finished curved edge to lay flat, clip triangle-shaped notches along the curved area of the seam.
4. Turn the fly shield layers on their right side to exposed the clean finished curved edge and iron the fly shield compartment flat.
5. Use any technique of your choice to clean finish the two vertical raw edges taht meet across from the finished curved edge. The easiest and least bulky option is to use an overedge stitch like serging or a zigzag stitch available n all home sewing machines.
6. To prepare the facing, cut a matching piece of interfacing using the facing piece as a guide. Make sure the interfacing's fusible side corresponds to the facing's wrong side. Fuse the interfacing to the wrong side of the facing as shown above. Use a protective cloth to shield the iron plate form the fusible adhesive.
7. Clean finish the outer curved facing edge using serging or a zigzag stitch, or any other technique of your choice.
8. A fly front application requires a shorter metal chain zipper that is anywhere from 4"-6" long depending on the indicated zipper opening on your garment patterns. In this example, a 7" inch zipper will be shortened to fit into a 4/5" zipper opening. Start by aligning the crotch seam edges together fabric face side stitching. Measure the zipper opening from the top of the seam downward, and pin the seam edges together starting at the bottom of the zipper opening. Pin perpendicular to the edges as shown above.
9. Stitching the seam only at about 2" down form the bottom zipper opening. Doing so will allow the seam edges and garment layers to be more flexible and lay flatter during the fly application process. The crotch seam is completed once the zipper and all its components are fully stitched.
Mark the desired placket topstitching lien using a hand basting stitch. Apply the basting through the garment layer on the side of the seam that will house the zipper placket. This line should mark exact shape and width of the final placket topstitch.
10. Align the straight facing edge with the garment's seam edge housing the final zipper placket, such that face sides are touching and the top horizontal edges align. Insert pins perpendicular to secure the edges together,
11. Machine stitch the facing the garment's seam edges at the designated seam allowance- 1/2" in this case. The bottom of the facing should extend below the stitched portion of the seam (at the bottom) onto the seam allowance edge.
12. Iron the facing seam with the facing layer and all seam allowance pointing away from the garment layer.
13. Place the zipper face down on the facing layer such that the left zipper tape edge aligns with the facing's seamline. Hand baste left zipper tape to the facing layer underneath to keep the zipper aligned. Machine stitched the unbasted, right zipper tape through the middle of the tape. You should use a zipper presser foot for optimal comfort.
14. Once the right zipper tape is stitched to the facing layer, flip the facing to the garment's wrong side to expose the placket's clean finished edge and insert a few pins perpendicularly through the garment and facing layers, keeping them flat and smooth in preparation for topstitching. Starting at the, topstitch the zipper placket following the hand basting as a guide. As you topstitch, you should only catch the the facing layer underneath and not the zipper tape. Remember, the zipper tape has already been permanently stitched to the facing layer in the step above.
13. From the wrong side of the zipper application fold the free seam edge at about 1/4" beyond the seam allowance and iron the fold to crease. Remove all hand basting from the zipper tape.
14. Open the zipper all the way and align the folded seam edge on the free zipper tape, such that the folded edge aligns at about 1/8" from the zipper teeth. Hand baste the zipper tape and garment's folded edge to secure.
15. With the zipper application on its wrong side and fully closed, place the fly shield over all the zipper components such that the shield's top edge aligns with the garment's top edge and its vertical straight edges aligns with the garment's seam allowance edge. Insert a few pins to secure then hand baste the shield; straight edge to the matching seam allowance edge underneath.
16. Open the zipper all the way down again and using a zipper foot, along the hand basted folded edge catching the zipper tape and fly shield underneath (as pictured above).
17. To shorten the zipper, pull the individual link from each zipper tape using a pair flat nose pliers at the are of the top seam allowance as shown above.
18. Trim the excess zipper at the top such that it is flush with the top horizontal edge. To secure the top of the zipper tape and prevent the slider form accidentally coming of the zipper track, machine stitch the top portion of the tape to the garment layer underneath, applying the stitch at the beginning of the zipper chain. Use a zipper presser foot to stitch right next to the metal chain and repeat this process on both sides of the zipper.
The fly front application is now complete! Once the garment's top edge is finished either into a waistband or another seam, the trimmed zipper tape will be encased for clean-finishing and the top of the zipper chain further secured.