How to Sew Knit Fabric
What is the purpose of sewing a knitted fabric by machine? Faster, simpler and neater, sewing machine piecing can transform a wool coupon, or even assemble hand-knit pieces. It allows you to make knitted pieces, sweaters and others, even without knowing how to knit. You just have to choose the right settings to avoid damaging your knitting!
Knitting includes all knitted fabrics, as opposed to woven textiles. Jersey is, therefore, a knitted fabric, just like thicker woollen knits, but it is finer and tighter than the latter. Sweater-type knitwear has larger stitches and a wide variety of thicknesses. It can be purchased by the yard or hand-knit for machine piecing. These are the techniques you will learn about here.
1. Choose the right needle to sew knitwear
Stitches are fragile! Sewing knitwear requires a special jersey needle with a rounded tip to avoid snagging or skipping stitches: the coarser the knit, the thicker the wool and the looser the stitches, the greater the risk of snagging. There are three types of stockinette needles, with sizes ranging from 70 to 90. The real difference is the roundness of the point.
– To sew a medium knit, choose a Ball Stitch Medium needle or SUK. This is the standard stockinette needle, also referenced 105/730, tapered but with a rounded tip. If you can’t find these markings, choose a needle simply marked “stockinette”.
– For a thick knitted fabric with a coarse stitch, choose a Ballpoint heavy, or SKF, needle: its tip is completely round and slips between the loosely packed stitches without snagging them.
– For thick, dense knitwear, use a Special ball point needle, or SKL, which is rounded but has a slight point at the end, capable of passing through large, tight stitches without damage.
Note: Ballpoint-heavy and special ballpoint needles are less common. If you can’t find them at the haberdashery, try a standard stockinette needle, which usually works. Choose a size 70, up to 90 for coarse knits.
2. Choose the right thread to sew knitwear
Since knitwear is stretchy, its seams must be stretchy to avoid breaking, starting with the thread.
– Choose a nylon or polyester thread, more resistant than cotton.
– It is possible to use a knitted thread, as long as it is thin enough to be threaded through the needle, and tight enough not to cause jamming.
– There is also foam thread, specially designed for the sewing machine bobbin: it is only visible on the reverse side and offers a better elasticity to the seam.
3. Choose the right stitch for knitting
Again, the stitch must withstand the threading of a collar or sleeves. It is, therefore, essential to choose a zigzag stitch that has enough stretch to resist the stretching of the knitwear.
– Many sewing machines have a special stitch for stretchy fabrics, called a stretch stitch, which is illustrated by a bias zigzag.
– Without a stretch stitch, opt for a simple, long, narrow zigzag stitch: set a stitch length of 2 to 3 mm, for a width of 0.7 mm.
– For a tight-knit, test the stretchy straight stitch or triple stitch.
4. Iron the knitted pieces with a pattem
To iron knitwear without shining the wool, you need to use a pattemoon, a piece of fabric that insulates the stitch from the iron soleplate.
– Cut a piece of cotton that is larger than the pieces to be ironed, otherwise you will have to move it as you go along.
– Wet it under the faucet, then wring it out well so that it doesn’t drip: it should be just damp.
– Place the knitted piece on the ironing board. Cover it with the cloth.
– Set the iron to “wool” or the setting that matches your knitting yarn.
– Iron the piece, then remove the pad and allow the knitted fabric to dry completely before moving it.
5. Prepare your knitted fabric for sewing
– As with any machine sewing, place the pieces of knitting to be joined right sides together.
– Pin them together with long, thin pins, stuck perpendicular to the future seam.
6. Before you sew, try it out!
Each type of knit fabric has a different thickness and elasticity, so there’s no one-size-fits-all setting: it’s essential to test to determine your own:
– If you’re using a yardage knit, have a scrap for testing. If you are hand knitting, you will need to knit an extra piece, at least 10 cm high.
– Reduce the tension of the yarn: the more elastic the knitted fabric, the lower the tension should be.
– Place the knitted fabric on the machine, insert the needle and lower the presser foot. Stitch!
7. Adjust your sewing machine settings
The real problem with sewing machine knitting is the feed: as the stitches pass over the plate and under the presser foot, they can pull and snag, or even refuse to advance or curl. There are several tricks to solve this problem, depending on the thickness and width of the stitches to be sewn.
– If the stitch is too tight or the stitch curls, reduce the tension of the thread again. Conversely, tighten the tension if the stitch is too loose.
– Also, reduce the pressure of the presser foot: the more the foot crushes the knitted fabric, the more likely it is that stretchy knitted fabrics will be distorted rather than drawn out. Dive into your sewing machine manual if you need to, then decrease the pressure to make sewing easier.
– If the knitwear gets damaged or snags, place a sheet of tissue paper between the knitwear and the plate, and/or the knitwear and the presser foot. Stitch normally: you will then just have to pull gently on the tissue paper to tear it without damaging the seam or the stitches.
– Push the knitted fabric, rather than pull it! Pulling it back behind the presser foot will distort the stitches without advancing the knitting. Instead, use both hands, flat on either side of the foot, to push the knitted fabric backwards. Be careful, if the stitch is likely to snag, don’t forget to use tissue paper.
– Test the training feet: depending on the machine model, there are special knitting feet or training feet. They facilitate the training of the knitted fabric to avoid the risks of deformation or hooking.
When you have found the right settings, stitch, without forgetting the stop stitch!
Note: two soft stitches are better than one stiff one. If your seam has good stretch, but you feel it lacks strength, reinforce it with a second seam, either on the side or on top.
What you need to sew knitwear
Dressmaker’s scissors
Iron
Sewing thread
Sewing machine
Fabric
