Sewing on Stretchy Fabrics

Sewing with stretchy fabrics has a reputation for being tricky. A few decades ago, it called for special handling of the fabric, given that sewing machines lacked some features that are now commonly available. In this article, we will explore how to sew three very different types of stretchy fabric.

In the process, you will find that even a fairly simple sewing machine today can handle these fabrics with ease, all while yielding perfect seams that can stretch with the fabric. For this article, we used a bernette 38 electronic machine. It is simple to operate and offers a wide variety of stitches to cover all the key bases.

Spandex (Also Known as Lycra and Elastane)

Spandex fabrics behave essentially like elastic and tend to be the stretchiest. This makes them especially well-suited for active wear of any kind (gym, sports, cosplay, etc.). The main challenge they pose is that they can stretch beyond the ability of the average thread to survive said stretch. That same elasticity can also cause the fabric to stretch out while being sewn, leading to distorted seams. To counter this, follow these simple guidelines:

1. Use a super stretch stitch on your machine. This stitch typically takes one sideways step before moving forward, resulting in a stitch that can extend forward quite a bit without stretching the thread. The right stitch type is the best step for achieving a good seam on stretchy fabrics.
2. Reduce the presser foot pressure. This is almost always a must when sewing with stretchy fabric. By reducing the pressure the foot puts on the fabric, it minimizes the risk of stretching the layers in an uncontrolled fashion while stitching them together. With full foot pressure, the fabric can overstretch and create a rollercoaster seam in the finished product. A good rule of thumb is to reduce presser foot pressure by half and test a seam.
3. Use a thread that has more stretchability, such as Mettler Seraflex thread. It is a polyester thread containing elastane, which gives it up to 60% stretchability. Technically, you could sew spandex with a straight stitch if using Seraflex and the seam would stretch along the garment without popping stitches. So, by combining a super stretch stitch with a stretchable thread, we are doubling down on ensuring the seam can stretch as far as needed without losing seam integrity.
   • Avoid cotton sewing thread with stretchy fabrics. They have a very limited stretch and will break readily when the fabric is stretched.
   • If sewing spandex with a regular polyester thread, like Mettler Metrosene, it has a 10-15% stretch by design and this, combined with the super stretch stitch, yield a seam that could extend out with the fabric’s stretch.

With the simple steps above, a perfectly smooth and stretchable seam can be sewn on Spandex with no special effort.

Neoprene (aka Scuba Suit Fabric)

While Neoprene is not as stretchy as Spandex, it is squishy (compressible) by nature, and that squishiness can lead to the fabric stretching forward along the seam to some degree. This can be further accentuated by the thickness of the material. While the stretchiness is nowhere near that of Spandex, it is a factor to consider while seaming. Here are a few pointers that will enable you to adapt the seam to neoprene’s properties:

1. Use a longer stitch to accommodate the bulk/thickness of the fabric. This is generally needed for thicker fabrics, so the thread bridges over the bulk and lies down properly between needle penetrations. Here, a 3 mm long straight stitch was used on 3 mm thick neoprene.
2. Reduce the Presser Foot Pressure. This will help prevent the layers of neoprene from squishing forward (stretch uncontrollably), resulting in a flat, even seam for the length of the project. In our sample, the foot pressure was reduced from the default value of 4, down to 3. This was just enough to accommodate the thickness of the neoprene fabric without squishing it forward under the foot. Remember to test.
3. Use a 100% polyester or bonded nylon thread. Cotton thread would not last long with the amount of stress a neoprene project would put on it, especially if the article will be used in a wet environment.
4. Consider using a non-stick needle for thicker neoprene. If sewing long seams at high speed, static can build up on your thread and could lead to loose or skipped stitches, especially where the relative humidity is low. A non-stick needle, like Schmetz Super NonStick, reduces the friction in and out of the rubber-like material at the core of neoprene and helps ensure a smoother glide of the thread.

With a few basic settings in place, sewing with neoprene is pretty straightforward.

(Stretchy) Jersey Knit

Jersey knit comes in a variety of weights and all of them share one property: stretchiness (albeit not as far as Spandex). While that makes it excellent for garments, it can pose a challenge at sewing time. The good thing is that with the right stitch and thread, it’s still a breeze to sew.

The following settings were used for this sample. They should feel familiar already, after sewing on spandex:

1. Use a super stretch stitch on your machine. As mentioned above, this type of stitch is the first best chance at getting a good seam on a stretchy fabric like jersey knit.
2. Reduce the Presser Foot Pressure by half. When combined with the super stretch stitch (above), it helps keep the fabric flat and flowing evenly under the presser foot, for a smooth and extensible seam.
3. You can use regular sewing thread with jersey knit. The super stretch stitch is usually enough to accommodate the level of stretchiness in such a fabric. As added insurance, use a polyester sewing thread like Mettler Metrosene for its 10-15% stretch ability.

The result is a fine seam that will accommodate the fabric’s stretch when the article is in use.

In summary, when sewing with stretchy fabrics, here are four basic guidelines that will keep you on track:

1. Always test your seam on scrap pieces first (if they are available).
2. Select a suitable stitch (e.g. super stretch).
3. When in doubt, reduce presser foot pressure. A good rule of thumb is to reduce it by half.
4. Select a suitable thread for stretch ability and wear resistance.

From there, enjoy sewing on knits and stretchy fabrics. They make such a wide variety of projects possible.