Elastic thread goes on the bobbin, not the needle, and you use regular thread on top
Elastic thread is a thin rubber core wrapped in polyester. It stretches when you pull it and snaps back when you release it. The standard method is to wind it onto your bobbin by hand, then sew with regular thread in the needle and elastic thread underneath. The elastic sits on the underside of the fabric, and when you pull the seam, the elastic stretches with it. This creates a gathered or shirred effect without having to bunch the fabric by hand first.
You can also use elastic thread in the needle if your machine allows it, but this is less common and requires a larger needle and looser tension. Most sewers find the bobbin method faster and more reliable, especially for beginners.
Key Takeaways
- Wind elastic thread onto the bobbin by hand at an even tension — do not use the machine's bobbin winder, which will stretch it unevenly.
- Use regular thread in the needle and elastic thread on the bobbin, then sew with the elastic side facing the fabric you want to gather.
- Loosen your top tension slightly so the elastic thread pulls the fabric without puckering or breaking.
- Test your tension and stitch length on scrap fabric first, because elastic thread behaves differently than regular thread and mistakes are hard to undo.
Winding elastic thread onto the bobbin by hand
Do not use your machine's automatic bobbin winder. The winder pulls too hard and stretches the elastic unevenly, which causes tension problems later. Instead, wind by hand at a slow, steady pace. Hold the elastic thread loosely between your thumb and forefinger so it feeds at the same speed the bobbin turns.
Place the bobbin on the bobbin winder shaft and turn it slowly by hand or use the machine's hand wheel. Keep the tension light — you should feel almost no resistance. Wind until the bobbin is full but not overstuffed; elastic takes up more space than regular thread, and an overfull bobbin can jam. If the elastic bunches or twists as you wind, stop and start over. Uneven winding causes skipped stitches and broken thread.
Setting tension and stitch length for elastic thread
Loosen your top tension by one to two numbers from where you normally sew. Elastic thread on the bobbin pulls harder than regular thread, so if your top tension is too tight, the fabric will pucker or the elastic will break. Start with a medium stitch length — around 2.5 to 3 millimeters — because shorter stitches can bunch the fabric too much, and longer stitches may not gather evenly.
Sew a test seam on two layers of scrap fabric first. Pull the seam gently to see how much it gathers. If the fabric bunches too much, loosen the top tension more or increase stitch length. If the elastic does not gather enough, tighten the top tension slightly or shorten the stitch. Write down the settings that work so you can repeat them on your project.
Which side of the fabric faces the presser foot
The side of the fabric with the elastic thread underneath should face the presser foot as you sew. This means the elastic sits against the feed dogs and the regular thread (on top) is visible on the other side of the seam. When you pull the seam, the elastic gathers the fabric from underneath.
If you want the gathering to show on the front of a garment, sew with the front facing down. If you want the gathering hidden on the inside, sew with the inside facing down. The elastic thread will always be on the underside of the seam, so plan your layout before you start.
Common problems and how to fix them
Skipped stitches: The elastic is wound unevenly or the bobbin is overfull. Rewind the bobbin by hand, making sure the elastic feeds smoothly and the bobbin is not packed too tight.
Broken elastic thread: Your top tension is too tight, or you are pulling the fabric as you sew. Loosen the top tension and let the machine feed the fabric at its own pace. Do not guide or pull.
Fabric puckers instead of gathers: Your stitch length is too short or the top tension is too tight. Increase stitch length to 3 to 3.5 millimeters and loosen the top tension by another half number.
Elastic does not gather enough: The elastic may be old or degraded, or your tension is too loose. Try a fresh bobbin of elastic thread and tighten the top tension slightly. If the elastic is more than a few years old, it may have lost its stretch.
Using elastic thread in the needle instead of the bobbin
Some machines and some sewers prefer elastic thread in the needle. This method requires a larger needle — size 90/14 or 100/16 — and a looser top tension than usual. You still use regular thread on the bobbin. The elastic sits on top of the fabric and creates a visible textured seam.
This method is harder to control and breaks more often than the bobbin method, especially on delicate fabrics. It works best on sturdy cotton or knit fabrics where you want the elastic stitching to be a visible design detail. Test on scrap fabric first, because the stitch can look uneven if your tension is not right.
Caring for seams sewn with elastic thread
Seams with elastic thread can handle normal washing and wearing, but they do wear faster than regular seams because the elastic degrades over time. Wash in cool water and dry on low heat to extend the life of the elastic. Do not bleach or use fabric softener, which breaks down the rubber core.
If the elastic loses its stretch after a year or two, you can resew the seam with fresh elastic thread. Unpick the old seam carefully, rewind a new bobbin, and sew over the same line. This is much faster than replacing the whole garment.
Frequently Asked Questions
Can I use elastic thread on a serger?
Yes, but only on the loopers, not the needles. Wind it onto the looper bobbins by hand, just as you would for a regular machine. Sergers create a rolled edge that works well with elastic thread for gathering knits and stretchy fabrics. Test on scrap fabric first because serger tension is different from a regular machine.
What if my elastic thread keeps breaking?
Your top tension is too tight. Loosen it by one full number and test again. If it still breaks, the elastic may be old or the bobbin may be wound too tightly. Rewind the bobbin slowly by hand, keeping the tension very light as the elastic feeds onto the bobbin.
Do I have to use elastic thread on the bobbin?
No, but it is the easiest method for most machines and fabrics. Elastic thread in the needle works on sturdy fabrics and creates a visible textured seam, but it breaks more often and requires a larger needle and looser tension. Try the bobbin method first.
Can elastic thread go through a regular needle?
Not reliably. Elastic thread is too thick and too stretchy for a regular needle. If you want to use it in the needle, use a size 90/14 or larger and loosen your tension significantly. Most sewers find this frustrating and stick with the bobbin method instead.
How long does elastic thread last in a finished garment?
Typically one to three years, depending on how often the garment is worn and washed. The rubber core degrades over time, especially with heat and sunlight. Wash in cool water and dry on low heat to make it last longer. Once the elastic loses its stretch, you can resew the seam with fresh elastic thread.