Couture Zipper FlyA precise designer method
Many pant designs today, from jeans to traditional trousers, use fly zippers. Everyone who sews has a favorite method for setting one. I like the following technique best. I first saw it on a pair of Yves Saint Laurent couture pants, and I’ve seen it on many other couture designs by Dior, Chanel, and Valentino.
In this procedure, the fly opening is machine-topstitched without the zipper. Then the zipper is sewn into the opening by hand. This may seem silly, but it works well for most fabrics, especially very thick ones. On the overlap, it eliminates the problem of machine topstitching over the zipper teeth at the bottom and provides greater control and accuracy at all stages of the zipper insertion.
If your pattern doesn’t have an extended facing for the fly, you can add one by drawing a line parallel to and 1-1/2 inches from the center front. On women’s pants, fly zippers usually lap right over left and are particularly attractive when worn with blouses with button closures at the center front. Jeans flies for men and women typically lap left over right.
Prepare the opening
Mark and stabilize the garment sections for the zipper installation first. Follow this method for a smooth, flat fly.
1. Thread-trace the center front and waist edge on the pant fronts. Mark the foldline for the underlap extension on the left front at least 5⁄8 inch from the center front. It can be up to 1-1⁄4 inches away. With a deeper lap, the placket lies flatter and the zipper won’t peek out on tighter designs.
2. Prepare foldline stays. Use seam binding or a 3⁄4-inch-wide strip of lightweight silk. I prefer the selvage from lightweight silk such as organza, chiffon, or china silk. The selvage is easier to handle, but…