Single Layer Easing, Crimping, and Crowding

Single-layer easing and crimping (otherwise known as crowding), are techniques I'd like to teach the whole world. With a little practice, they work magic for shaping garments to fit over our curved bodies. I use these techniques regularly to shape pocket openings, necklines, armholes, and sleeve caps.

If you have been sewing for any significant length of time you have noticed this fact:

When sewing through only one layer of fabric, the tension of the stitches often cause the fabric to pucker.

Usually this effect is undesirable as we want our seams to be flat and smooth. However, it works to our advantage when we want to build just enough fullness into a seam or edge to allow it to delicately curve over a convex area of the body. I'll call this technique single-layer easing.

How much fullness we get by sewing through one layer of fabric depends on several variables:

• Fabric content, weave, and weight. Obviously, lighter fabrics will draw up more easily and heavier fabrics, like denim, may not draw up at all. Synthetics tend to draw up readily (too much so.) Closely woven fabrics such as microfibers and gabardine also have a tendency to draw up in an undesirable way. The best candidates for controllable, attractive easing are light to mid-weight natural fibers (cotton, wool, and silk) in regular, plain weaves.
  
• Thread tension. Higher tension leads to more puckering.
• Thread content. Polyester and nylon threads are elastic and cause more puckering as stitches relax. Cotton thread causes the least.
• Presser foot opening. The larger the opening, the more movement the fabric under the needle is permitted and the more puckering will occur. (This is why we use a presser foot with a small hole when stitching on lightweight fabrics.)
  
• Needle plate opening. For the same reason as above, more puckering will occur with a larger needle plate opening.
  
• Stitch length. Longer stitch length causes more puckering. Think about it...there is more fabric b/w each stitch to draw up under the tension of the threads. There is also less thread, less give, in the seam, so it cannot relax as flat as a seam with a smaller stitch length and more thread can.

Even given all these variables, you will quickly come to understand your machine's particular tendencies and capabilities to ease fabric. My Pfaff, for example, has a large, 9mm needle plate opening. Most of my presser feet also have this large opening. This fact means that my machine has a tendency to draw fabric up very easily. I can usually ease fabric into shape by simply sewing through the single layer with a slightly increased stitch length.

For some of you though, you will have to use a technique called crimping or crowding to get your fabric to ease into shape.

Crowding is what it's usually called when we place the left index finger tightly behind the presser foot, impeding the fabric's progress under the foot, and causing it to crowd up under there, causing easing.

I believe I first saw this technique on a Nancy Zieman show many years (15?) ago on her PBS series Sewing with Nancy. You will find it in many sewing books. It is also the principle of some gathering presser feet, and differential feed on a serger. You impede the feeding of the fabric under the foot, causing it to buckle up underneath.

To crowd fabric, place your left index finger firmly behind the presser foot, really wedging it slightly under the back of the "heel." Keep the pressure there as you sew, and you will see the fabric bunching up behind and under the foot. Release the pressure and begin again at regular
intervals, allowing the fabric to move on through. Here, I've removed the ankle screw so you can more clearly see my finger wedged behind the foot.I also use my thumb to gently push the fabric towards the presser foot, increasing the crowding effect: This is a technique that takes a little practice. Tear some muslin into strips and go for it. Then, before you try it on your actual garment piece, do a test run on a scrap of that fabric as well.

Given your particular situation - type of machine, fabric, and amount of ease required - you may only need to stitch through a single layer of fabric, perhaps with increased stitch length or thread tension, or you may need to use your finger (crowd) in order to achieve the amount of shaping you need.

My suggestion to you would be to gather some scraps of your garment fabric. Start with your machine at a slightly higher than normal stitch length and normal tension. Stitch through one layer of fabric. Evaluate how much easing, results. If it's not enough, start making some adjustments to machine settings. Try a longer stitch length. If that does not help, you might increase thread tension a notch or two. If you are still not achieving the desired amount of eased in fullness, try placing your finger behind the presser foot.

Here are some quick examples I stitched on my Kenmore, a.k.a, my "little blue machine", which has a needle plate opening of 7mm. I used relatively straight grained scraps of cheap muslin.

This shows a regular stitch length, regular tension:
It is relatively flat, as is the next sample, with an increased stitch length and still regular tension:
Here I've also increased the tension and I finally have some easing of the fabric. See the puckers beginning to form within the stitches?This is probably enough easing for most V-necklines, and I would stop here in those instances. But I might want more easing for a sleeve cap, or around the side bust part of an armscye. In those instances I would add some crowding to my stitching, and get a result with much more shaping, like this:Note how easily this curves around the ham here:
Once steam pressed, the easing will become completely inconspicuous outside the seamline, but the shape will remain.

If you do some crowding on your sample and find you are getting too much fullness, you can simply hold less pressure on your index finger or release the fabric from behind the foot more often.

I rarely use gathering threads to ease fabric anymore. Most of the time, single-layer easing or crowding will provide just the right amount of fullness for subtle, attractive shaping over the body's curves. It seems to provide a more evenly distributed easing than gathering threads. It works at edges such as necklines or pocket openings as well as for interior shaping points such as sleeve caps, elbow points, or back shoulders. It's easy to do, and fits easily into the construction process with little forethought or planning.