One of the biggest excuses that people use for not selecting an invisible zipper is that they can’t find it in the color and length they need. You don’t need an exact color match because the zipper is “invisible,” and won’t show. And, just like a standard zipper, if you can’t find the length you want, you can buy one that is longer than needed and shorten it. You just have to create a new stop at the bottom with a wide zigzag (4.0mm width and .03 length). (A) Excess zipper can then be cut off 1 inch beyond the new stop.
Unlike other zippers, the invisible zipper goes in before the seam is stitched together. I like to stabilize the fabric behind the zipper with two strips of interfacing, cut in the non-stretch direction, 3/4-inch wide and 1 inch longer than the zipper tape itself. (B) By doing this, you will eliminate any rippling, and by cutting the strip slightly longer than the zipper tape, you will eliminate the poking out effect often seen at the bottom of the zipper. If the zipper will be crossing a seam such as in a contoured band or yoke, don’t interface the seam allowances until after the horizontal seam is sewn. Press the seam open and trim down the seam allowance to 1/4-inch in the area of the seam allowance. On the wrong side of the garment, press on the narrow interfacing strips to the seam allowance. (C) While at the iron, unzip the invisible zipper and press the coil flat, pressing from the cloth side of the zipper. A check to make sure that you have pressed the coil flat enough is to zip up the zipper. If the zipper tape stands straight up on its edges, you have done a good job.
Unzip the zipper and finger press 1/4-inch strips of Wonder Tape on each side of zipper tape on the Right Side of the zipper. (D) Peel off the paper on one side of the zipper. Position the top of the zipper teeth so that your sewing line at the top of the garment will be 1/16-inch above the top teeth. With the Right Side of the zipper against the Right Side of the garment and the zipper tape facing toward the seam allowance, finger press one side of the zipper tape into position.
For best results, purchase a metal invisible zipper foot which fits your machine. (E) Starting at the top of the zipper, slide the teeth into one of the grooves on the foot, the groove which allows you to sew on the tape. Sew down one side of the zipper tape until the invisible zipper will not allow you to sew any further; this is about 1 inch from the bottom stop. (F) Zip up the zipper and make a mark where the stitching of the first side stopped at the bottom and the location of the crossed seam so that it can be positioned at the seam on the corresponding side. (G) Unzip the zipper and peel off the paper of the Wonder Tape on the loose side of the zipper. Place the garment pieces Right Sides up and butting together so that you will be matching up the garment with the loose side of the zipper without twisting the zipper. Match up the marking on the zipper tape with the crossed horizontal seam, don’t worry if one side of the zip seems further down from the top of the fabric, matching the seams is far more important. (H) The top can be trimmed off a bit later. Anchor with Wonder Tape the Right Side of the zipper tape to the Right Side of the seam allowance, with the tape in the seam allowance.
If your zipper is going across a horizontal seam, cross pin the marking on the zipper tape with the seam so that no shifting will occur as you sew. Repeat the steps you did when attaching the first side, sewing down the zipper until you reach the marking on the zipper tape which tells you where you stopped sewing on the opposite side.
Replace the invisible zipper foot with a regular zipper foot. The next step is to close up the seam under the invisible zipper. (I) To do this successfully, your first stitch must start where the last stitch at the bottom of the zip is visible. The regular zipper foot allows you to do this by moving the needle away from the inside of the zipper foot toward where you want to sew without the foot getting in the way. Then using your regular sewing presser foot, close up the remainder of the seam to the bottom of the garment. The last step is to anchor the bottom of the zipper tape to the seam allowance so that it will not flip up when starting the zipper. (J) Using a press cloth, press the zipper flat from the right side.
Sandra Betzina designs Today’s Fit patterns for Vogue Patterns and is a regular contributor to Vogue Patterns magazine. She is also the author of Fast Fit, More Fabric Savvy, Power Sewing Step-by-Step, and Sandra Betzina Sews For The Home. In addition, she has produced eight DVDs, and conducts week-long sewing workshops limited to 10 people. For information visit www.sandrabetzina.com.