torstai 9. elokuuta 2018

Skipped stitches when sewing lycra

This one is in English. Finnish version here.

Made in cooperation with Make Bra,

A sewing machine makes stitches by tying together upper thread with bobbin thread every time the needle goes through the fabric. If this doesn't happen precisely right, a stitch is skipped and you see an extra long thread in the stitch row – or no stitches at all! Sewing lingerie materials may be a bit trickier for some sewing machines and you might need to make adjustments to produce a flawless result.

First of all, always use a new needle and high quality sewing thread. A needle can be blunt or damaged even if you can't see it with the naked eye. When spending time and effort sewing something you'll wear for a long time, it's worth using a brand new needle! Cheap sewing thread is often less smooth and can get caught on dense materials like lycra and elastics, so look for tight woven and sleek threads. The price is usually a quite good indicator of thread quality.

Before you begin, check the main things in your machine: Is your sewing machine threaded correctly? Is upper thread tension right? An average tension for the most projects is 4 or N. You might need to loosen or tighten it to get the result you want. Use some scrap pieces of your lingerie fabrics to test the stitch and adjust tension accordingly. When testing, take two layers of fabric, because that's what you are sewing too. It might be necessary to test with elastics etc. too. Too tight upper thread may cause skipped stitches, too loose leaves unwanted loops. And remember to keep your sewing machine clean and oiled, it really makes a difference!

I suggest using a super stretch needle (HAx1SP) if you want to minimize the risk of skipped stitches. An universal (standard) needle works just fine on most occasions, but to be on the safe side, pick a super stretch or stretch (code ending -S or -SES). Super stretch needles can be used in most of the modern sewing machines using needle system 130/705H. (HAx1 is equivalent of this code, SP means special point.) It has been specially designed to avoid skipped stitches and has a wider groove for the thread and a special tip resembling a snake's head with a lightly rounded point. Normal stretch needle has some of these features too. I wouldn't suggest using a jersey needle, because it's made for heavier knits with more looser texture and doesn't pierce dense fabric as well.

When sewing lycra or other dense fabrics, it's important that the thread doesn't get caught in the hole the needle makes. A bigger size needle makes a bigger hole for the thread to go through, so sometimes you have to change to a 80/12 or a 90/14 size needle. But don't overdo it, too big holes in fabric are not wanted and using a too big needle and can damage elastics and other fine materials.

The sewing machine must feed the fabric smoothly and evenly to produce a flawless stitch. Sometimes lycra and especially several layers of elastics, FOE etc. can make the machine to jam and not feed the materials enough. If you have a special walking foot available or Pfaff's IDTfeature, try using it. These special presser feet systems feed the fabric also from the upper side, so the fabric feeds much more evenly than by just normal feed dogs under the fabric.

Check, if you can adjust your machine's presser foot pressure. It's usually a dial on the top or on the left end of your machine. Find the right pressure by trying it on scrap materials. Try loosening it for sewing thin layers of stretchy fabrics like lycra and adding pressure, when working with foam and many layers. If your fabric tends to stretch under the presser feet, try loosening the pressure.

The presser feet pressure is vital for avoiding a phenomenon called 'flagging'. It happens, when needle is moving upwards and the fabric rises with it instead of staying flat on the stitch plate. This causes skipped stitches and stretching. With enough presser foot pressure this can be avoided, but unfortunately lycra is quite prone to this problem. Also choosing a bit bigger needle size can help.

The risk of skipped stitches varies by materials and their properties. Some lycras can be more difficult to sew than others. Often a dense lycra with plenty of stretch and rubbery feel causes most skipped stitches.

When sewing thick layers or cross sections of seams and elastics, you may have to increase the presser feet pressure or use a walking foot. There's also a clever tip to make these heavy sections and crossings easier for your machine: try pressing them together with pliers or take a hammer and wrap it in scrap fabric (to avoid markings in your sewing project) and give them a bang! This really makes a difference. Also ironing the parts helps and it is recommended anyway for more finished look and easier handling.

When sewing foam lining, zigzagging the edges makes it easier to work with. The zigzag stitch pushes the foam together and makes it easier for the needle to go through it.

And if your needle hits something hard, like a pin or metal parts, change it. The needle is an important, but a relatively cheap part of your sewing process.

Left Super stretch, right universal. Material very dense swimwear lycra.