​The Conventional Way To Topstitch A Centered Zipper On Both Sides

A conventional centered zipper application features two equally spaced topstitched placket, one positioned each side of the zipper. The zipper is perfectly centered along the opening with the zipper teeth aligning with the abutting opening edges. 

The easiest and perhaps most correct way to topstitch the centered zipper plackets is to tackle one side at a time and stitch from the bottom up. It also helps to hand basted a guideline of each placket topstitch so it can be followed in the topstitching process. ​

Starting form the bottom zipper opening, stitch horizontally from the seamline outward following the hand basting line. At the placket's bottom corner, pivot the stitch vertically and continue stitching following the hand basting until you reach the top of the zipper. One topstitched placket is now complete, let's tackle the second one: 

Starting at the same point along the seamline stitch horizontally away form the seam and the other stitch until you arrive at the placket corner. 

Pivot the stitch upwards and begin stitching vertically until you reach the top of the zipper. 

 To secure the bottom stitching, use a hand-sewing needle to pull the two topstitch threads to the wrong side of the zipper application. Hand tie the two threads together to lock the stitching thus prevent it form unraveling. 

Once stitched, remove the hand basting using a seam ripper. Both plackets should be equally spaced on each side of the seam featuring a smooth stitch application and perfectly straight placket angles. ​