Seraflex Thread Review • Heather Handmade

Learn all about Seraflex thread by Mettler. It’s a stretch thread for knit fabric sewing projects, but it has strength and durability.

I’ve said it before and I’ll say it again, it takes time to figure out sewing knit fabric. And as much as I love working with knit fabric, it’s always great to find a new product that will make it a little easier. Something that will help both those just learning and those who have been sewing for many, many years.

I tried out Seraflex thread by Mettler* to see how I liked it. I tried it on several different knit fabrics to see how it would work and how it would stretch.

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What is Seraflex thread?

Seraflex thread* by Mettler is a stretch thread that is not elastic thread. It is thin like regular thread with up to 65% stretch.

It’s made from raw material PPT and works perfectly with knit fabric. It is not made from rubber or elastic like shirring thread. It can be treated like regular thread.

This thread is meant to use with straight stitches on knit fabric and the thread stretches to stretch with the knit fabric. It comes in lots of different colors so you can always find the right color for your sewing project.

It’s slightly shinier than regular all-purpose sewing machine thread, but I will have to be careful not to mix it up with my other threads.

How can I use Seraflex thread?

Seraflex thread is meant to be used in the top thread AND the bobbin thread. Seraflex needs to be used in both places on a sewing machine so that the seam can stretch as much as possible.

Also, the tension needs to be loosened as much as possible to give the seam the full possibility of stretching. I sewed Seraflex on a couple of knit fabrics to see how it would sew and how it would stretch.

Seraflex Thread on Cotton Spandex Jersey

I sewed a Seraflex straight stitch on cotton spandex jersey, and then I stretched it to see how it worked. The stitch was nice and straight, and it stretched very well with the fabric. I didn’t have any tightness.

Seraflex Thread on Double Brushed Poly

I sewed a Seraflex straight stitch on double brushed poly, and then I stretched it to see how it worked. The stitch was nice and straight, but I felt like it needed to stretch a little more. I should have loosened the tension a little bit, and then there would have been more stretch.

Seraflex Thread on Rayon Spandex Jersey

I sewed a Seraflex straight stitch on rayon spandex jersey, and then I stretched it to see how it worked. The stitch was nice and straight, but I felt like it needed to stretch a little more. I should have loosened the tension a little bit, and then there would have been more stretch.

Seraflex Thread on Swimsuit fabric

I sewed a Seraflex straight stitch on swimsuit fabric (nylon spandex) and then I stretched it to see how it worked. The stitch was nice and straight, and it stretched very well with the fabric. I think it would stretch well with the swim fabric, but I would probably do a slight zigzag when doing swimwear, even with this thread, because the last thing I want in the pool is popped seams.

Seraflex vs Eloflex

When I was working with both threads, they felt very similar to me. The thread weight and sheen were the same. And when I pull each thread by hand, they felt like they stretched the same amount.

When I sewed one piece of knit fabric with both Seraflex and Eloflex, I felt like the Seraflex had a little bit more stretch. Both threads stretched well, and I could probably use them interchangeably.

I’ve only used Eloflex on clothing and over time I found anything (swimsuit and workout leggings) with a high amount of stretch and high stress pulling still needed a zigzag stitch to give it the stretch it needed.

If you make something using this sewing project, I’d love to see! Please share it on social media with the hashtag #heatherhandmade and tag me!