How to Sew Smooth Sweater Knit Seams

Smooth side seam on a shaped, double knit jacquard sweater -- this relatively stable sweater knit was washed before cutting.

Back in October of 2016 I had the pleasure and honor of chatting with Chuleenan of CSews about sweater knit fabrics and related topics. While conducting a giveaway, we asked readers what they imagined to be most challenging when sewing sweater knits. The most mentioned challenging issue turned out to be rippled seams; that is, the challenge some face in getting a sewn sweater knit seam to lie flat and not pucker. I'm happy to say that there are solutions to this problem. Some sweater knits are more difficult to work with than others, but there's usually some method or tweak that will give you the smooth seam you desire. Though I've discussed aspects of this issue before, my goal is to tackle the subject in more depth today.

Smooth Seams Start Before You Sew

Smooth seams begin with well prepped fabric. Just as you would wash any other fabric before you even think of cutting, the same is true for a sweater knit. Sweater knits are generally washed at the knitting mill that produces them, but wax (to help the fabric knit smoothly on the industrial knitting machine) and soil (sometimes present with natural fabrics that haven't been bleached or dyed) may remain in the fiber. Your careful washing of the fabric will do wonders to remove any debris that remains stuck in the yarn. The washed fabric is fuller with a little more body and stability.

Washing may impart enough stability to keep the seams from stretching when you sew. Indeed it's the stretch of some sweater knits that causes them to ripple when sewn. Both natural  and synthetic fabrics will yield a better result after washing. The key is to squeeze water from the fabric without stretching. (Roll fabric in towel and squeeze. Never wring.) Allow the fabric to dry flat, without stretching, and allow the fabric to find its natural size. Remember to serge or zigzag any cut or unfinished edge before washing and to follow the care instructions for the fabric.
Very unstable fabric used for hat with no rippling at the seams -- I used light pressure and a walking foot.

Too Much Pressure

So you've washed and allowed your fabric to dry. You're testing your stitches on scraps of fabrics to get your settings on your sewing machine just right, but you're still not getting smooth seams? Your fabric is becoming stretched out as you sew. It could be your presser foot that's causing your troubles. Or more precisely, it's most likely the pressure of your presser foot on the fabric.

Imagine as you sew, the feed dogs on the machine below your fabric diligently moving your fabric forward. The downward pressure of the presser foot keeps your fabric flat on either side of the needle. If the presser foot delivers too much pressure, however, it will work against the feed dogs. The standard presser foot sometimes holds the fabric in place allowing the already stretchy fabric to stretch even more as the feed dogs below the fabric work to move the fabric forward. The result is a lumpy, ripply seam.

One solution is to reduce the pressure of the presser foot. On some sewing machines reducing this pressure is a simple turn of a knob. (See your sewing machine manual for location of this knob, if available.) On other machines the option is not available.

What is available for most machines is a walking foot, also known as an even feed foot. This foot will work with the feed dogs of your sewing machine. The walking foot provides an extra set of feed dogs above the fabric. When the walking foot is not integrated into a sewing machine as with certain industrial machines and domestic Pfaff machines, a bar on the walking foot attachment connects with the needle clamp screw of the sewing machine. As the needle moves down, the fabric grippers (feed dogs) on the foot move away from the fabric. The grippers lower to meet the fabric again as the needle raises. Feed dogs above and below work in tandem to advance the fabric forward and the sweater knit is fed evenly through the machine. This synchronized action will prevent stretching in many situations.

Serger/Overlocker Set Up 

Whether you're using a serger to finish your seams or for construction, the differential feed ratio must be set up properly. This setting is a ratio comparing the speed of the front feed that brings the fabric to the needles with the speed of the rear feed that moves the fabric away from the needles. A setting of 1 means the feeds are going at the same speed. That setting, however, would stretch out most sweater knits. A setting between 1.5 and 2 will work for most sweater knits. With this setting the front feed is moving 1.5 to 2 times faster than the rear feed, preventing the sweater knit from getting stretched out.
In this pic the front feed is to the right of the thread tail and the rear feed is to the left.

As with your sewing machine, you’ll also need to set a proper tension and stitch size.

Step Away from the Edge

Many knits will be more unstable with little recovery closer to the cut edge. They may even have gotten stretched out from less than careful handling. Working with a wider seam allowance and sewing further away from the cut edge is sometimes all that's needed to produce a smooth seam.

Use Temporary Stabilizers

So many good products exist from spray-on starch (commercial or homemade) to wash away and tear away products made specifically for sewing. Personally, I prefer the wash away stabilizers because picking out remaining pieces of tear away can be a chore. (See how I use wash away stabilizer on difficult fabrics here.)

Steam is Your Friend

Steaming a slightly puckered, overstretched seam is definitely allowed and recommended. Hold the iron at least a half inch above the seam, 2 inches or more if working with synthetics. (Try this on a scrap first!!!) Allow the steam from your iron to penetrate the fabric. Then, pat the fabric gently into place with your hand. Let the fabric dry undisturbed to shrink back to size. It's amazing what steam will do, especially with cotton, linen, wool, or silk. But this will only work if the pucker is tiny, so don't depend on this tip if your ripples are major.

Sometimes it's just a matter of practice, learning how to handle various sweater knits, and becoming used to how your machine handles these fabrics. I would love to hear any suggestions and experiences you've had in the comments below.

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How to Cut and Sew a Minimum Waste Sweater

If the diagram above makes your eyes cross and gives you a pounding headache, then this article isn’t for you. Though a zero waste specialist would consider my design quite simple, I admit to being quite happy with the way it turned out.

I'm pretty sure that similar tops have been made thousands of times before. The cutting and sewing took about a minute. (I exaggerate.) The planning took a couple of days, but not full days, just every now and then over a period of two days in January.

I broke a few rules with the wool sweater knit I was using. We're usually told to work with the stretchiest direction around the body. (I've certainly said that enough times.) But Saint Cloud sweater knit is lightweight and relatively stable. I found it stable enough for me to use with the stretchiest direction hanging as the yoke; the rest of the bodice is lightweight enough not to pull on the yoke and stretch it out. Even without shoulder seams or stabilization, it works.

Most of the sweater's details were described in my previous post about this sweater.

As I look at my layout today, I see a few possible variations:
  • Rotate the layout 90 degrees so that the orientation for each main piece switches. This way I could probably use a heavier fabric, since the yoke would better support the weight of the bodice. That is, lay it out and sew the sweater so that the finished sweater hangs...

  • Add bands to the sleeves (as cuffs) and at the hem. It would use more fabric, but it fits into my sewing with rectangles theme. :)
  • Use one sweater knit fabric for the yoke and a totally different one for the bodice. 
  • And of course making a pocket with the cut out fabric from neckline.
Scraps from the trimming the hems and the neckline
Perhaps my wool sweater is seasonally inappropriate as the temperature reaches above 80° F today in New York City. As Fashion Revolution Week 2017 comes to an end, however, I'm glad that I could post my pattern for a minimum waste cut and sew sweater today. The Fashion Revolution must take place each day, of course.

How to Cut and Sew a Minimum Waste Sweater -- The Pattern

This sweater is comfortably loose. I used a yard and a quarter of relatively stable sweater fabric. With half-inch seam allowances it fits size 34" bust with 5 inches of ease. These are basic instructions only. Sew and finish seams and hems in your preferred method. (I sewed the main seams with a narrow zigzag 0.75 mm wide by 2.5 mm long. I steamed seam allowances to one side, then top stitched. I used a twin needle to hem the sleeves and the bottom of the sweater.)
  1. With a felt tip erasable fabric marker or tailor's chalk, draw lines on sweater knit fabric, as indicated by solid black lines in diagram at the top of this page. 
  2. Cut on marked lines. 
  3. With a felt tip erasable fabric marker or tailor's chalk, mark the dotted blue lines on yoke/sleeves piece.
  4. Using the template, trace, then cut out shape for the neckline.
  5. Sew binding to neckline.
  6. Pin together, then sew Front aa to Front Yoke aa.
  7. Pin together, then sew Back bb to Back Yoke bb.
  8. Pin together, then sew Sleeve c1 and c2 and Side Seam c3 and c4
  9. Pin together, then sew Sleeve d1 and d2 and Side Seam d3 and d4
  10. Sew hems.
If you have any questions or see any mistakes, please let me know. Everything's a rectangle so it's pretty easy to scale up or down. Download the neckline template here. No sign up is necessary, but if you'd like to receive my newsletter (sweater knit fabrics, sweater fashion, tips and techniques for sewing sweater knits), subscribe here.

Last update 12Nov2017

The Return of Providence

I'm extremely happy and excited to reintroduce Providence to the collection of sweater knits in the shop. Some of you, who may have read this blog in the days when I personally machine knitted most of the shop fabric, may remember posts about the Providence stitch pattern, fabric, and eventual sweater. While it's wonderful to have  the opportunity to bring back a favorite, I'm also pleased that this Providence is new and improved.

The newness comes in the dimension of width. While the old Providence, knitted on my vintage Passap machine, was limited to a relaxed 24 inches wide, the new Providence is 60 inches wide relaxed (updated Feb. 22, 2017), stretching crosswise about 40%. Most people will want to go down a sewing pattern size when using this fabric. Do be careful with any sewing pattern identified as "negative ease"; like many sweater knits, while the fabric stretches well across the width, the recovery (return to pre-stretched size) is slow. In other words, the fabric isn't suited for a body conscious sweater dress. This is 100% wool, 0% spandex.

Frankly, I'm ambivalent about the greater width. A narrow width is definitely easier to handle. If a fabric can be knitted to the width of the wearer, a narrow fabric will require less cutting and will produce less waste. On the other hand, only with custom knitting can a home sewer be provided with fabric of a custom width. When providing fabric to a variety of sweater knit enthusiasts, I'm learning it's best to go wide (especially with the fancier or more intricate designs). And so I have. A sewer can more effectively layout the pattern pieces this way. Allowing for the generous crosswise stretch, some will be able to cut an entire sweater from a single yard.

The new Providence is a little bulkier than the old, now knitted with a slightly heavier yarn. It's a beautiful medium grade, worsted spun yarn from a New England spinner and yields a fabric with amazing stitch definition and a hand knitted look. My knitting contractor referred to the fabric as "slow knitting" (with all those double tucks for texture) and having "lots of body".

Fabric Care

I'm sure you've heard this next bit of business before, if not on this site, then elsewhere. It's about being sure to prepare fabric before cutting and sewing. Always sew a zigzag stitch or overlock stitch on any raw or cut edges on the wool knit before washing. Follow the same procedure you plan to use when laundering your finished item. Remember agitation, hot water and hot dryers will shrink most wool. (Prepping Providence properly will also soften and fluff it.) Here are my recommendations for prepping or the regular washing of wool sweater knits.
  1. Launder similar colors together. Mix a small amount of mild detergent or soap in sufficient cool water to completely submerge your fabric. (Do not use Woolite. Woolite contains "optical brighteners" which can remove natural oils and "dry-out" the fabric. Do not use bleach.) 
  2. Allow fabric to soak for 15 to 20 minutes. No need to agitate.
  3. Rinse gently in cool water. You may use fabric softener, if you like.
  4. Remove excess water by rolling fabric in a towel and squeezing gently or by using the gentle spin cycle only of a washing machine.
  5. Gently smooth the fabric into shape on a flat surface, being careful not to overstretch the fabric. 
  6. Allow fabric to air dry away from direct sunlight. 
    OR you may have your fabric dry cleaned.

    I recently read about a technique of ironing sweater knits through a wet cloth in order to prep them for cutting and sewing. I can't recommend it, only because I've never tried it! Though I have a couple of exceptions, I tend to avoid pressing and ironing sweater knits. I've also heard of people using the steam cycle of a dryer to prepare wool. I've never tried the steam cycle of a dryer. (I don't have access to a dryer with steam.) I'm guessing that the steam cycle of a dryer might shrink and/or felt the fabric somewhat, because of the heat and movement?

    So far I've only worked with a 9 x 9-inch swatch of Providence. My swatch had no shrinkage when I hand washed it, as described above, and let it dry flat.

    Providence sweater knit is now in the shop. I'm planning to make a jacket!


    Last update 22Feb2017