For stretch sewing, use polyester thread in your needles (sewing machine, overlocker and coverstitch) for strength and durability.
If you decide you love sewing stretch fabrics, it is worth investing in stretch thread or woolly nylon, which you can use in the loopers of your overlocker or coverstitch machine. It can also be used in the bobbin of your sewing machine (wind it on by holding the spool in your hand and using the automatic winder on a slow speed). By using this option, you will get a little more give in the seam and it will be softer on the skin which can be important for those with skin sensitivities.
What is the difference between stretch thread & woolly nylon?
Essentially both are nylon threads. The difference is that woolly nylon usually has more flexibility and is a little ‘fuzzier’. Meanwhile, Maxi-Lock Stretch features a smoother touch and thicker texture.
If sewing cotton Lycra and woven fabrics, Maxi-Lock Stretch is a popular choice because it can handle heat better than woolly nylon, and you don't need to change thread when moving between different types of fabrics.
Stretch thread can be used for rolled hems too (only needed in the upper looper). This creates a lovely full stitch. Maxi-Lock Stretch is a popular choice for this as it is fuller and for its ability to withstand heat better. If you want to conduct a heat test, you can do so using extreme temperatures. When woolly nylon melts, it completely disintegrates. Polyester and Maxi-Lock Stretch are not affected.
The advantages of stretch thread
Many choose to use this option because it’s lovely and soft and smooth for the wearer. It allows for more stretch in your garment and makes snapped threads less likely to occur when the garment is worn. It is loved by machines and produces less fluff than some cheaper quality threads.
For decorative reverse coverstitching or rolled hems, it creates a lovely full finish for ultimate contrast!
So what about woolly nylon?
Woolly nylon is also a great option and can be more available in physical stores. If you are making garments that you plan to iron or throw in the dryer, it is best to avoid woolly nylon and stitch with Maxi-Lock Stretch!
How to use any kind of stretch thread
Use stretch thread in just the upper looper or upper and lower looper of your overlocker. You use polyester thread in your needles.
For coverstitch, use stetch thread in the looper only with polyester in the needles. When reverse coverstitching, stretch thread creates a beautiful full finish with ultimate contrast for your garment.
When using stretch threads, you may find you need to reduce your looper tension down to almost nothing to get a beautiful balanced stitch. After cutting your garment, use some scraps to sew some test stitches before you get started to check if you need to make adjustments.
How to wind it into a bobbin
Stretch threads are a great option for the sewing machine, especially when working with twin needles as they can help to avoid or reduce tunnelling. When adding stretch thread to a bobbin, either wind it by hand or hold the spool in your hand and machine wind on the slowest speed setting to ensure thread is not overstretched when applying.