On Zippers in Knits
I made a Cowichan-inspired jacket many years ago, and it was perfect. I absolutely loved it. Until I sewed the zipper in. Then it was a disaster: I had chosen the wrong length and type of zipper, and then I did a rush job of sewing, by machine.
So I cast any thoughts of zippers out of my mind. For twenty years.
I was in New York City last fall. The weather was cool and crisp, the right time of year for jackets. And every stylish woman I saw was wearing a leather motorcycle jacket. And no matter how they were styled or the age of the wearer, each one looked fantastic. By the time my friend arrived for lunch, wearing hers, I knew I had to have one, too.
But I’m a knitter, so I decided to design and knit it. I was about halfway through the knitting when I realized that the zipper details I was planning would require … well, zippers. Like, three of them. And I’d have to sew them in.
The first measly six-inch sleeve zipper took me about four hours. But by the time I was done, I realized everything I’d done wrong the first time around.
And so, to save you a sweater disaster and many hours of unpleasant learning, Kate’s Guide to Zippers in Knitwear.
In the MDK Shop
Lesson 1: Choose the Right Zipper
If you’re making a jacket or cardigan, make sure you get a zipper that fully separates. That is, a zipper for which you can separate the two parts. (You know, like on a coat.) These are called, handily enough, Separating Zippers.
The other type—think of the fly of your jeans—separates at one end, but not the other. This is the type I used for my jacket sleeves’ cuffs. Be careful, though: I initially bought a bag zipper by mistake, and that one is closed at both ends.
Consider not just the length, but the weight: A zipper for knits needs to be heavier than a zipper for woven fabrics. Good quality zippers will be labelled with a number that indicates the width of the coil/teeth, when closed, in tenths of cm. I used a #10 for my jacket, which has teeth that are a full 1cm (10mm wide). This is pretty extreme, but #5-8 aren’t unreasonable for knit fabrics.
The one at the top has a coil-style closure, rather than teeth. These are too light. The one at the bottom is plastic pretending to be metal. The center one is the best choice for a heavier weight knit fabric.
A zipper with traditional metal rather than plastic teeth is generally a better weight for a knit jacket; choose plastic teeth or a coil-style zippers for lighter fabrics.
Lesson 2: Consider the Fabric You’re Sewing To
The problem with sewing a zipper into a knit is that you’re sewing something stiff and stable—the zipper tape—onto something that isn’t. If the knit fabric relaxes after the zipper is installed, then you’re going to have puckers; if the knit fabric is stretched as you attach the zipper, the you’re going to have a bubbled, buckled zipper.
For best success, you want to inhibit the stretch and movement of the knit fabric where the zipper will be attached. There are a couple of ways to do this.
Use a tighter and more stable edging where the zipper will be installed. For example, on my jacket, I wanted the zipper to be exposed, so I needed the simplest possible edge on the fabric. I worked a slipped stitch edge, and kept it fairly tight.
If you want the zipper to be hidden, work a picked-up i-cord edge on your knit fabric. Ensure it’s reasonably snug, pulling the stitches tight as you go. The zipper tape will hide nicely under the i-cord.
If your garment has a ribbed or other type of band worked after the fact, consider the possibly-rather-radical-step of working it separately and sewing it on, rather than picking up the stitches. And make sure your bind off is firm—this is not a place for a Jeny’s Surprisingly Stretchy method. You’ll then have a stable edge, and can then attach the zipper either to the seamed join, or the bind off edge.
Or take a tip from those ubiquitous Scandinavian colorwork sweaters: ribbon. Hand sew a length of woven/grosgrain ribbon along the edge of the knit fabric, on the inside to provide a tidy base to sew the zipper to. Or sew it on the outside to create a decorative effect. Either way, the ribbon will stabilize the fabric and give you a good place to pin.
Learn from Kate’s Mistakes Part 1: Pay for a good quality zip. You don’t want to have to do this a second time when a cheap one breaks or gets stuck.
Lesson 3: Wash Before You Put the Zipper In
You should always block the pieces before you put a garment together. Just like pre-washing woven fabrics, you need to bring the fabric to its final, correct shape and size before you finish. To block, wash the garment pieces the way you’ll wash the finished garment.
If, after the wash, the edges of the opening are still extremely rolly, steam or lightly press them to make them behave. Caro Sheridan brilliantly recommends using blocking wires to stabilize the edge you’re sewing to – feed one along each edge of the garment, before you pin.
Learn from Kate’s Mistakes Part 2: Do it by hand. You’ll need long sewing pins, strong sewing thread in a color that contrasts both the zipper and the garment, and in a color that matches your garment, and a sharp hand-sewing needle.
Lesson 4: Pin and Baste and Sew
Lay the garment pieces flat. Open/separate the zipper, and carefully pin the tape along the edge of your garment, placing pins every inch or so, perpendicular to the direction of the zip. Close the zip and make sure it all aligns and lies tidy.
The zip is pinned along a slipped stitch edge, ready for basting.
The edge of the knit fabric is about a quarter inch away from the teeth. You want the zipper visible, not the tape. It does pull away a little once it’s sewn in.
In this case, I want the zipper to be hidden when it’s closed, so I’ve worked i-cord at the edge.
When pinning, make sure that the i-cord just covers one side of the teeth.
Using the contrasting color thread, baste it in. This is just to assess the placement, so use long stitches—half an inch (a centimeter) or so. Work from the right side of the garment, up and down in the space between the first and second stitch of the knit fabric (the same column you work in for mattress stitch).
I’m working in the column between the first, slipped, stitch and the second stitch of the row.
Take all the pins out and try the garment on to make sure it’s well placed and the fabric isn’t puckering or uneven. Ensure it looks good with the zipper open and closed.
Once you’re happy with the basting, then using the matching thread, sew the zipper in, using smaller stitches, closer together. Always work from the right side, still in the same column, so you can ensure your stitches are aligning with the knit fabric.
Try it on again.
And if that’s good, remove the basting. Then use the matching thread to whipstitch down the sides of the tape on the inside, just catching the inside bump of the knit fabric.
If you’re using ribbon, sew it on the inside, just inside the edge stitch, and then sew the zipper to the ribbon.
The ribbon not only stabilizes the edge of the knit fabric, but it gives you a wider base to pin to.
Alternately, sew the ribbon on the outside and sew the zipper so that the knit fabric is sandwiched between the zip and the ribbon.
Learn from Kate’s Mistakes Part 3: Be patient. This is not something to do in the final hour before you go to bed, in half-light in front of the TV, after a glass or wine or two. This is a quiet weekend morning activity.
Learn from the Experts: All my sewing books tell me to sew both sides of the zipper tape in the same direction. Any tension or pulling on the fabric is then in the same direction on both sides. It can help things look that little bit tidier.
Learn from Kate’s Mistakes Part 4: If you don’t like it, put your big-girl pants on, undo it and start again. If you don’t like it now, you’re not going to come around to loving it over time.
Lesson 5: Wash/steam After It’s In
To make it gorgeous and tidy and perfect, it’s worth another steam or wash. Because you’re going to wear this thing with great pride, and everyone is going to want to admire your zipper success. Trust me.
Save it for Later
Don’t need to install a zipper right now, but want to find Kate’s wisdom on the subject later? Here’s how to save this article in your MDK account with one click. Want to try your hand the great zippered design Kate is wearing? Take a look at her design The Wild One.
A good teacher is very rare, particularly on the Internet. You have rounded up some great ones like Jen and Kate. So clear and well thought out, and all else that it takes to be so clear. Also, as someone who has never sewn in a zipper on knitted fabric, but several on woven ones, I found that some fabrics are just easier to get good results with, especially as a newbie. So Kate’s tips on finishing the edges are additionally welcome because they help to compensate for those times you might have a looser, lighter, even floppier fabric such as this one I think in Vogue recently (probably the summer issue) where a motorcycle jacket was actually knitted in lace (at least I think it had a zipper). So beautiful but daunting to achieve. So Kate is my superhero of zipper tutoring, among other topics she has covered so well. Thanks Kate and thanks, Kay and Ann. (Sometimes I think knitters and knitting professionals can conquer the world. What’s the matter with everybody else?)
Yup. Vogue Spring Summer 2017. Thanks, Ravelry. I couldn’t find my copy.
Ann Weaver, another MDK contributor, has a fabulous class on putting zippers into knitted garments. I highly recommend taking it!
It’s a shame there is no picture of a finished product from inside and outside
My mother (she who taught me to knit) would use grosgrain ribbon on the inside of a sweater for a zipper or to reinforce button bands. I have an example, somewhere …. and if you look at older knitted sweaters, say cardigans, they also have grosgrain ribbon on the inside of the button bands. It’s not a new trick, but a great one to know and use. Thanks, Kate.
Thank you for your excellent timing. I have been replacing the ribbing and front bands on a vintage Norwegian sweater and have stalled on knitting the button band with 8 tricky button holes. Light bulb moment: forget the button holes and install a zipper with i-cord edging. I have installed zippers in knitwear before and have found that the hardest part is finding a zipper to match and fit. Off to go zipper shopping and maybe I’ll be wearing that sweater by this weekend!
When this jacket was mentioned yesterday, I had to run over to Ravelry to see it, I swooned. The design! The zippers and Jul fasteners! The welts! The combination of Ultra Alpaca and Alafoss Lopi! What a creative mind at work. It is the Oscar winner of 2017 knitting.
I may never be brave enough to attempt The Wild One (although this zipper tutorial makes a difference), but as one commenter said on Ravelry, I will buy this pattern if only to read and possess it.
Thank you Kate!
This is wonderful! I have only tried to sew in a couple of zippers, on felted items, and Kate has shown me how I could do it better. Thank you, Kate! And I love the caveat, “This is not something to do in the final hour before you go to bed.” I call that “11 pm knitting.” If I encounter a problem at 11:00 pm (or later!), I do not rip back right away. I put–OK, sometimes throw–the knitting down and try to do something soothing before bed, and look at the knitting in the clear light of next day!
I haven’t put in a zipper yet thank for showing how to do it very. Informative
I’ve often wished I had the skill even to contemplate putting a zipper in a sweater, so this article is both practical and inspirational. Since my confidence is shaky in this area I would also love advice whether there is a gold-standard brand for zippers, or alternatively brands that everyone who sews knows will not work properly.
Also, any rule-of-thumb about width of grosgrain ribbon?
No single brand of zippers, but take a stroll thru your closet and see what zippers you love-or dread! Notice —is the pull shaped or wider or smaller? How does it lay when it is closed? What do the teeth look like and how do they feel when the zip is open or closed?
Then go to Joanne’s and bribe the ladies if you must and try the zippers out. Many are not sealed and you can “try before you buy”. Are the tapes so stiff they would mess up the drape? are the teeth too rough and they would snag? And can you hand sew or would it require Thor’s hammer to pull a needle thru? (Back stitch is the most sturdy way to hand sew a zip after you are sure about the placement after basting and trying on)
As for ribbon, 1 cm minimum up to 3 cm is a reasonable range. Look close for the fabric content. Polyester is common and it won’t shrink but it may melt if you zap it with an iron.
Signed- a sewer who knits
Thanks a great article on sewing in zips.
Kate, I just realized I commented on twitter but not here. Thanks for such a clear description and especially the shortlist of Don’t Do This-es. I have never put a zipper into a knit and probably wouldn’t have considered doing it, as I am intimidated by even putting a zipper into fabric – but now I have moved Zippered Knit into the Column of Possibilities.
The one time I put a zipper in a sweater, I used a trick I use when sewing garments–baste the two sides together. Then you can line up the zipper with the exact middle, baste it in, remove the center basting, and carefully sew the zipper in. It ensures perfect centering so the zipper ends up hidden when closed, and also even placement along the zipper to prevent puckers.
Yup, this works brilliantly in most cases!
It’s a little different for this jacket, since I wanted the zippers to be exposed rather than hidden…. that is, I couldn’t baste the fabric of the two sides of the opening together, since I didn’t want them to meet or touch in the finished jacket.
Instead of using pins, you may want to consider using clear scotch tape.
I always seem to have problems with zippers that shrink. Well, rather the tape shrinks and the zipper does not. Any hints to avoid this issue?
It’s not a problem I’ve run into myself, I’ll be honest.
My first question/pondering is about whether this applied to knit garments or sewn garments that you were machine washing? Speaking from the knitting side of things, I’m typically only putting zippers into garments that I’m handwashing, so they’re not necessarily going to experience the sorts of conditions that trigger shrinkage….
And, of course, the quality of the zippers themselves can vary enormously. I know that I’m always tempted by the bins of dollar-zippers, but as with so many things, it’s usually worth paying a little more to get something that’s going to last a good long time.
I don’t know whether that helps or not… perhaps if you can give me a bit more detail about when this happened, and in what circumstances, I might be able to provide more detailed advice?
What a great reply! I haven’t tried zips in knits because of all the commercial clothing I’ve had that ended up with those awful wavy zippers. I’ve also had the same problem with pre-washing those invisible zips for skirts and so on and finding them hopelessly wavy to the point that I just assume I’ll hide a skirt opening in a pocket with wovens and not bothering to try a slimmer look with a zipper.
Thanks very much! I’ve been hunting around on the net for a while, trying to find an article to tell me the best way to plant a zipper on the front of my husband’s hooded vest. I think I’ll do the I-cord to bind off now. Been trying to find the best bind off for a zipper on a knit. I’m also knitting a garter stitch facing, so this all but guarantees this will be a pain in the tuchas. Never could do things the easy way…LOL
This is the best explanation I’ve found for hand sewing in a separating zipper. Thank you so much! But, in all my looking I’ve not found the answer to the issue that’s keeping me from starting to sew. I have the zipper all pinned in, I know how to backstitch, I have matching color thread, but how do I sew through the plastic end at the bottom end of the zipper tape?
Good explanation zips in knits! What to use if grosgrain is not available? Tape?
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