Thursday, 26 September 2013

Working With Stretch Fabric - Needles

Stretch fabric is knitted, rather than woven. You can get some woven fabrics with elastic fibres, like stretch denim or stretch poplin - these have minimal stretch and can be treated like a standard woven. For now I'm focusing on t-shirt fabric, ponti and really stretchy lycra/spandex stuff.

Because of the difference in construction, you usually need a ball point, rather than a universal needle. This allows the needle to push between the gaps in the knit, rather than piercing it. In a woven fabric, you want to pierce a hole so you don't snag a thread and create a pull in your work. In a knit, if you break the strand, you get holes. Ballpoint needles may be sold as ballpoint, jersey or stretch needles. To the best of my knowledge, jersey and ball point are the same, but stretch needles have a slightly different shape/eye which makes them more suitable for super stretchy stuff like lycra. Get those if you're doing swimwear.

Pointy for woven fabric, rounded for stretch fabric.
Like universal needles, ballpoint needles come in a range of shaft sizes (I've seen 70/10 - 100/16) with the smaller numbers being suited to the lighter, finer fabrics, and the larger numbers for the heavier denser fabric. The number will be printed on the shank. Some brands have a built in magnifier on their cases to help you see it (I think Schmetz does, but looking at the Prym pack in front of me I can't see one).

Sometimes you can get away with a universal needle on stretch fabric. Its easy to test. Before you sew your garment, grab a scrap of your fabric and do a test run. Pull it out and hold it up to the light. If you're seeing any holes forming around the seam / stitches, you need a ball point needle. Change it now, save yourself the disappointment. These little holes have the potential to run - just like a snag in a pair of stockings or a knitted sweater.
It's not going to get better.
Potentially you might also want to use a twin needle for hemming (although not for construction). Personally, I don't like them. The idea behind them is that you will get a similar effect to the standard hem finish (coverstitch) on stretch wear. I find the tension is always a problem, and am happy to leave the whole twin needle thing for decorative stuff on regular fabric. But if you want to have a go and mess with your tension until it comes up satisfactorily, go nuts. And then, please, tell me how you did it. Because I love you, here's a link to some people at the sewing org who seem to have the twin needle thing, err, all sewn up. It should give you a row of double stitching on the front, and a zigzag on the back.

If you are wondering about coverstitch, just to go on a tangent here, it is this stitch:

Which you will have no doubt encountered on the bottom of every t-shirt/pair of leggings you own.

Sadly, that's not a stitch you can do on a regular domestic machine. For that, you require a specialised coverstitch machine, or an overlocker with a coverstitch function. It's a bit fussy to work with (because if you sew without fabric in there, even one itty bitty stitch on the handwheel, the whole thing jams up) BUT I think worth the trouble. Unfortunately, my overlocker/coverstitch machine is sitting in storage on the other side of the planet. Bummer.


  1. Thanks! I'm saving this to re-read. :-). I need all the help I can get as I prepare to practice knits in the near future. :-)

  2. Good to hear your views on the twin needle hem business. I haven't tried it yet but planning to give a go.
    I didn't know about needle cases with a built in magnifier, I must buy in future. I can spend ages right underneath a lamp turning the shank ever so slightly back and forth trying to read!

    1. I used to have a magnifier in my sewing kit. Very much worth it.

  3. Hey Zoe
    I made a swim suit for a friend in 2003 and used the twin needle zig-zag at the back method for the elastic edges. It worked well. You zig-zag your elastic on first then turn it over and do the twin needle from the outside to get the coverstitch look. Sat nicely and looked the real deal.
    You can buy twin needles in a variety of widths so I'd go for one that is probably the widest you can get (for your machine and the elastic you are going to use!).
    It wasn't hard with the tension as we read the machine manual and I'm pretty sure they should all have a section on twin needles. If not may be a function (the brother machines at school that are about 4 yrs old have a twin needle function so I'm guessing it does an auto tension change, haven't tested it though).
    Also you can get a nice effect pin tucking with the twin needles too!
    I use the coverstitch on my Baby Lock every now and again and it always look great on my sample and goes @^*! on my real garment. So I need to investigate why.
    Another elastic edger that can be interesting is the three step zig-zag, I have used this for fold-over-elastic and it works a treat. (Bernadette — Needlewitch — has some great thin coloured with metallic bits which I'm going to use soon!)
    Loving the Blog Zoe makes me think about lots of stuff for school.
    Have you looked into button holes, that seems to be the bane of my existence at work as well as different zipper applications for a perfect finish. We so need to do a prerequisite unit and make them all do samples. Samples are so valuable, I still look at mine from high school.
    Anyway waffling now…. Lovely chatting the other night too.

    1. OK. Well I can see I will have to have another go! Thinking about the elastic idea - if you're sewing onto the elastic that probably would stay smooth because the elastic wouldn't buckle (forming the pin tuck effect, which is not what you want for a fake coverstitch).

      I've used the 3 step zigzag on elastic before, I think Mum's machine had a wavy one which I've seen used on commercial bras and knickers.

      I'll get back to you on twin needles.