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Wavy Zippers: Swayback? Bad sewing? What’s wrong!?

mollytov | Posted in Teach Yourself To Sew on

 Since I started sewing this summer, I haven’t quite gotten an invisible zipper right. They keep turning out wavy, bubbling and puckering the garment, never laying flat. With back zippers, I think the problem might be that I have swayback, and hadn’t thought to do swayback alterations, but my side zips are turning out mighty strange as well. Maybe I need to interface them, and maybe it’s something else. I put up pictures to illustrate what I mean, and an article begging for help on my blog mollytov.com

Any advice or helpful links would be greatly appreciated! I’ve been creeping this forum and all your projects for some time now, and it’s been super helpful to me in starting my own sewing journey! Mucho love Threads homies!


  1. marymary | | #1

    Molly, one of the best things you can do to install a zipper correctly is to use a strip of iron-on interfacing in the seam .  I looked at your blog pictures.  The way a sewing machine works causes the wavy seams.  You don't need a heavy interfacing.

    On fabrics that I don't interface, like fleece, I use double sided soluble tape to place the zipper. If it is a separating zipper and I have seams to match, I mark the zipper with chalk so that I can be sure I line up both sides of the zipper in the correct place.  Of course, this only works on washable fabrics because you have to wash away the tape. 

    1. mollytov | | #2


      That sounds great! Thanks so much for the advice. I'll try it tonight with interfacing for sure :D

  2. stillsuesew | | #3

    Your fabric is stretching.  The previous answers will help you, but you can also put zippers in by hand,  if necessary.  It really doesn't take as long as yuo might think and can look really professional.

  3. dbroncofan | | #4

    Craftsy free class

    Bernina sponsored a free class on craftsy.com for zipper installation.  I have been sewing for a while and had troubles on my first zipper installation in over 30 years.  After ripping it out 5 times I got something close.

    Wish I had seen the craftsy lessons before trying it.  I have just watched the first lesson, on slot zippers and learned at least 3 things that I did not know.  I will advise.

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