How to Use Stretch Thread For Sewing Knit Apparel

Welcome to the eighth lesson in the Beginner’s Guide to Sewing Knit Apparel! Download the ebook for free!

I’m stupid excited about this lesson guys. Because I sewed a whole lot of knit projects before I found out about stretch thread. In that time, I experienced way more popped stitches than I liked. Even with using my serger, or proper stretch stitches on my sewing machine. Little pop here, little pop there. And a super annoyed Jessica restitching things again and again.

Enter stretch thread!

In past tutorials, I’ve had people ask me

“Wait a second! How are you top stitching with a straight stitch on your sewing machine and not getting popped stitches?” The answer is stretch thread.

In past lessons, we have talked about different ways to create a nice and stretchy stitch using twin needles, sergers and special stretch stitches on your sewing machine. But sometimes you just want a plain old straight stitch and no fuss ammiright?

Whether it be a bias neckline or a hem, you can’t overlook the clean look of a pretty straight stitch. And with knit fabrics, a straight stitch is usually unpractical. That is until you get yourself some stretch thread. Now when I say stretch thread I’m talking about two specific kinds of thread I’ve grown to love immensely. The first is Maxi-Lock Stretch Thread.

Maxi-Lock Stretch Thread

Maxi-Lock is a brand name of thread. Their stretch thread is a textured nylon that has the look and feel of yarn. Check out this picture and you’ll see it kind of has a fuzzy texture to it.

When you pull on the thread, this loose fuzziness gives it the ability to stretch out considerably until it is taut.

Wooly Nylon

The second is wooly nylong. Wooly nylon is even more stretchy than Maxi-Lock Stretch Thread!

When you zoom in on the wooly nylon you’ll see that it’s the fuzziest of them all. The only downside to wooly nylon is it is considerably more expensive than it’s Maxi-Lock counterpart.

Editor’s Note: Has your knowledge of stretch thread grown? Use that knowledge on the Womens ABB Leggings!

Maxi-Lock Stretch vs Wooly Nylon

It’s really straight forward. Wooly nylon thread is more stretchy than Maxi-Lock, but Maxi-Lock is a lot more affordable, coming in at about half the price of wooly nylon. So if you’re doing a lot of sewing, you’re going to get the most bang for your buck going with the Maxi-Lock.

Super Scientific Comparison Chart:

Maxi-Lock Wooly Nylon
Super Stretchy Super Duper Stretchy
Less Expensive More Expensive

How To Use It

My first recommendation is to always have stretch thread in your bobbin when you are topstitching or sewing garments that are really form-fitting. It is going to add a glorious amount of stretch to all of your sewing machine stitches.

The second place I recommend using it is in your loopers on your serger and/or coverstitch machines. Even with serger stitches, you may find that garments with a lot of negative ease (swimwear, leggings, etc.) will still occasionally pop stitches with regular polyester or cotton thread. Get rid of this issue by using stretch thread in your loopers. If you feel like you aren’t getting enough stability with the stretch thread in both loopers, just use it in the lower looper.

Note: When you use it in your machines you will likely have to mess with your tension. In my serger, I have to increase the tension on it to keep my seams from being too loose and to also keep the thread from unraveling as it moves through the loopers. However, in my coverstitch machine, I have to decrease my tension to prevent my top stitches from tunneling. Just make sure to test it on some scrap fabric to perfect your tension before using it on your apparel projects.

To summarize:

Different Kinds of Stretch Thread: Maxi-Lock Stretch and wooly nylon
Benefits: Prevents popped stitches because it is a stretchy thread
Downsides: It's expensive compared to all purpose thread
Garments You Should Use It On: Tight fitting clothing and topstitching
How to Use It: In your bobbin and loopers

And there you have it my friend. You are all wrapped up with the Tools To Make Sewing Knits Easier section of our Beginner’s Guide to Sewing Knit Apparel. Next up we’ll be going over how to sew some of the trickier pieces in knit apparel, specifically neckbands, sleeves and hems.

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Learn All About Maxi-Lock Stretch Thread and Wooly Nylon and Why You'll Love Them For Sewing Knits

32 thoughts on “How to Use Stretch Thread For Sewing Knit Apparel”

  1. Hello! Great information! I am about to sew my daughter a bathing suit for her swimming lessons and came across your blog. I bought the stretch thread and I have one doubt about the bobbin. When you wind it, do you use the standard settings for the bobbin winding? I am wondering if as the machine is winding the thread it is also stretching it in the bobbin…
    Any advice?

    Thank you!!


    1. Hi Denise! When you use it in the bobbin you should wind it by hand 🙂 Similar to elastic thread, you don’t want it stretching as it’s being wound. Good luck with the swimming suit! I love stretch thread for my swimwear!

  2. Hand winding makes me a little sad, lol. But, I just picked up some stretch thread for the first time, so I can top stitch the neckbands on my daughter’s rompers that pull up through the neck. I prefer the finished look of the topstitch, but needed the stretch to get the opening over her cloth diapers!

  3. Hi there, question for you:
    When machine sewing (not serging) do you only use the stretch thread on your bobbin? Or would you use it on the spool as well? I just want to be sure I understand, because the last time I tried stretch thread, it went horribly wrong, lol. Thanks in advance!

  4. I have a few questions! I am planning to sew an Ice skating dress by scratch with 4-way stretch Spandex (a.k.a. LYCRA) using My Juki MO-644D Serger to do most of the work. I also plan to appliqué a ‘flame’ design (this flame design is Spandex as well) onto the dress using my normal Sewing Machine (Viking Emerald).

    When I begin sewing the dress on my Serger, will I only use two Stretchy Wooly Nylon thread spools on my Looper threads and normal thread on my Needle threads? If the answer is yes, what type of thread will I have to use on my Needle threads?

    The same questions goes for my Viking Emerald which will be used for appliquéing red flames (I will be doing the zigzag method). I understand that I will have to wind red Stretchy Wooly Nylon thread in the bobbin and not use it on the main spool. Therefore, what type of thread will I have to use for the main spool?

    (Also I just realized that I will have to apply an invisible zipper in the back, which I assume I will have to sew it on with my Viking and not my Juki Serger (because the serger would cut it off with the knife lol). Would Wooly Nylon still work when sewing the zipper on?

    I recently saw on an ice skating pattern that suggested getting 100% polyester for sewing an ice skating dress. But after hearing about Wooly Nylon, I disregarded this suggestion. However, will 100% polyester be good for when I can’t use wooly nylon as asked about above?

    Thank you in advance and I am looking forward to your response!


  5. I have tried and tried it o get wooly nylon threaded through the last opening in the looper of my coverstitch macbhine but to no avail! Do you have any tricks?

  6. Can this Maxi-Lock product be used in a general sewing machine to shir a waistband or smock a top, in place of the elastic thread that is normally used? Seems more efficient to buy this massive spool, if that will work.
    Thanks for your post!

    1. Hey Rachael! I wish I could say yes, but stretch thread isn’t nearly as stretchy as elastic thread :/ For shirring you need the elastic stuff.

  7. This is also great when using the overcast foot & settings on your sewing machine …
    The overcast foot keeps fabric aligned for a 1/4″ seam or smaller & is a perfect choice to use when making french seams on chiffon, lightweight or heavier cotton fabrics. Start first by cutting a 1/4″ seam, then line up fabric on left side of bar for a 1/8″seam, then fold over fabric & line it up against long bar to sew a 1/4″ seam as usual- all done …
    The loop & zigzag stitches with the maxi-lock thread stretches as well as looks like its been sewn on an overlocker serger machine …

  8. So the trick to sewing with the Maxi-Lock thread is to use it only in the bobbin on a regular sewing machine? My machine is not a serger or anything special, but a good machine. I wanted to use it to hem some jersey knit dresses for my daughter in law. I have had a terrible time! I have taken out the hem at least 4 times because the thread is bunched up on the back side so bad that I believe I now have bald spots! I know I need help but don’t know where to go. Please tell me you can help me. I’ve been sewing for more than 50 years, and all I need is to be told HOW to make this work!!!!!

  9. Hey! Thanks for this post! I have Maxi like stretch and really love it. I’ve been using it for swimwear and leotards… But I’m wondering if I should start using it in my loose fitting jersey apparel as well. Do you have a strong opinion either way on that?

    1. I enjoy using it an all of my wrist and ankle hems, but use the regular stuff for the other construction seams. It’s a bit pricey so I like to save it for the parts where I feel it’s most necessary 🙂

    1. You can use any regular polyester thread for attaching elastic. It is more about choosing a stitch with stretch versus a thread with stretch when it comes to sewing with elastic. 🙂

  10. Hi, Jessica. Just saw your blog. I have a Singer 9980 and was told I can only use all purpose thread in the bobbin. Do you think this is true, because I wanted to use a decorative thread
    in both the bobbin and the top. What are your thoughts on this delimma?

    Thanks for your time.

    1. Hey there! I sew with a Singer as well with similar functionality as the 9980 and I haven’t had issues with using topstitching or stretch thread in the bobbin. You may just need to hand wind it if it’s something stretchy.

  11. I have a question about my cover stitch and serger machine.Can I use Maxi-Lock Stretch with my two needles , then wooly nylon on my loopers. Have you tried this before ?

    1. I wouldn’t recommend using any stretch thread in the needles for regular construction seams. They won’t be stable enough. I only use it in the loopers (or the bobbin in the case of a sewing machine).

  12. Do any brick and mortar stores sell wooly nylon? Is there a better brand than another? Also, if you use regular polyester thread for the needle and one of these stretchy for the bobbin, won’t the regular polyester keep the stretchy thread from stretching? Sorry, kinda new to sewing.

    1. Hi there! I don’t have a preferred brand of wooly nylon. Most often I use Maxi-Lock stretch. And since the wooly nylon or Maxi-Lock stretch have a “give” to them, you can use regular thread for your needles and still achieve a good stretch from the lower threads (whether that be from a bobbin or serger loopers). It isn’t recommended to use stretch thread in the upper needle because it can compromise the stability of your stitches.

  13. Should I still use a zig zag stitch for extra assurance I won’t pop a stitch while using the maxi? In addition do you recommend back stitching or tying ends?

    1. Yes, you will still need to use a stretch stitch 🙂 I always backstitch, myself, but you can secure your ends to your preference.

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