Tips for sewing smoothly and problem-free with knit fabrics on a regular sewing machine (and not a serger). Knits are a favorite of sewists but the sewing process is usually not. These tips may save you this time.
In this article I will cover:
- How to sew Knits
- Select good knits
- What special sewing machine accessories do you need to sew knits?
- How to prepare knits for sewing?
- How to cut Knits for sewing?
- Which way should the knit be cut for clothes?
- How to handle knit fabric while sewing ?
- What interfacing to use ?
- How to sew seams on knits ?
- What to do with fabric edges ?
- How to sew hems on knit garments ?
- How to prevent stretching of edges on knits?
How to sew Knits
Select good knits
Why buying good knit fabric to sew is important?
Fabric is everything in sewing. I am sure you know that. And there are so many different types of knit fabrics out there. Some of the knits can drive you crazy. If you get a good knit fabric, half of your job is done.
There are many reasons why knits are favorites for dressmaking. It makes great fitting garments which drape well and are comfortable to wear. It is also easy to care. The main dressmaking knits are jersey knit, double knit, interlock knit, nylon tricot, interlock, velour, sweater knit, and terry knit.
First, check whether the knit fabric is resilient. If you stretch the fabric, it should return to its resting position. Do not stretch at the edges, but stretch somewhere inside. See if the fabric has formed un-necessary bulges after it has returned. If it has, do not buy it.
Stretch it crosswise and lengthwise and see the differences in the stretch. If the fabric do not return to the resting position it will mean that it will sag with wear and wash.
Cotton knits are very comfortable on the body and the most preferred for dressmaking. Cotton jersey is good for t-shirts and tops. The fabric edges of jersey knits curl. Read more on Jersey fabric here.
Interlock knits do not curl like this at the edges. Rib knits are very good and have a good stretch and make great figure-fitting garments. Cotton/spandex, single-knit fabrics are a favorite fabric for making exercise clothes because of their excellent stretch and recovery as well as comfort.
Different knits stretch with great variations. Some do not stretch much and some stretch like crazy. 2 way stretch knits contain spandex fibers with super stretch. They are great for making leggings, swimsuits and such figure hugging clothes. Some knits like Sweatshirt knit, double knits do not stretch much.
Buy a little extra to ensure having enough fabric for the garment after preshrinking.
Finding the right side of your knit fabric is also important – though some knits look the same on both sides. Stretch it (gently) along the crosswise grain- the fabric will roll to the right side. That is how you know. Mark this and start your sewing.
What special sewing machine accessories do you need to sew knits?
Overlock machine or Serger machine would be nice to own to sew with knits. These machines make stretchy stitches that suit the flexibility of knit fabrics. A three- or four-thread serger stitch is the best stitch for sewing knits. Overlock machines sew, cut, and trim the fabric all at the same time – they make a straight stitch on the front of the fabric and on the back a zigzag type stitch.
On an ordinary sewing machine a zig zag stitch/ presser foot is preferred to sew the seam.
Use a walking foot instead of the regular pressure foot – it smoothly moves the fabric and there is no stretching of fabric.
Use a ball-point, universal or stretch needle to sew seams and hems. 70/10 needle can be used for lightweight knits. 75/11 stretch needles for medium weight knits. For a thicker knits you can use 90/14 needle.
You can also get a twin needle to sew hems. It can give you a coverstitch like hem in one go – just use a stretch twin needle.
You can use a 100% polyester or cotton/polyester blend thread – on top as well as on the bobbin. Regular cotton thread will pop/snap under pressure because of the stretch of the fabric. Polyester thread has that slight stretch which will adapt to the stretch of the knit fabric.
Nylon thread or Wooly Nylon thread can be used on the bobbin because of the stretch for sewing with twin needle.
Buy stay tapes – they prevent edges stretching out of shape.
Fusible web is great to sew hems on skirts, pants and dresses made of lightweight knit. Fusible web is fused with knit in between the folds of fabric of the hem to give it stability.It can make the fabric firm and prevent stretching.
How to prepare knits for sewing?
Knit fabrics shrink after washing, even more than some woven fabrics, so prewash knits before sewing to prevent shrinkage afterward. Do not wash in hot water, the fabric will shrink more. Buy a little more to account for shrinkage.
Iron out the wrinkles before cutting.
Find the grainline – There is no selvedge in knit fabrics and you cannot pull thread of knit to know the grain line like you would do for a woven fabric.You maynot be able to find the fabric grainline by aligning the edges as you would do with a woven fabric. Aligning the edges is not dependable.
You can straighten the fabric- this is very important in knit fabrics otherwise it would not hang right. Better way is to align the visible vertical ribs of the knit. If they cannot be aligned the fabric would not hang correctly on the body.
If you have a tubular knit fabric, cut the tube open along a rib.
Two major problems with knits are that the edges curl and its stretch makes it hard to sew. The stretch can lead to overstretching and this should be prevented.
How to cut Knits for sewing?
Ensure that the fabric is not stretched as you mark and cut the fabric.
Knit fabric is prone to holes so use pins as less as possible or use ball point pins. Attach pins to the seam allowance.
Some knits ravel easily so you have to be careful as you mark, pin and cut.
Most knits have a right side and a back side like Jersey fabrics. To determine the back of the fabric stretch along the crosswise cut edge. The edge will curl to the right side. Interlock knits look same on both sides.
Ensure that the grain line is straight as you cut. You can check that the wales and courses of the knit fabric are perpendicular to each as you keep/mark the pattern.This will ensure that fabric is on the right grain. Read more on grainline of fabric here.
Which way should the knit be cut for clothes?
Make the crosswise stretch across the body as you cut the pattern – this ensures good fit. Do not cut otherwise thinking you will save some fabric- the fabric will hang in a different way that what you want.
With knits containing spandex you should cut so that the greatest stretch of the fabric is across the body.
How to handle knit fabric while sewing ?
One problem with some knit fabrics (with lycra content) is that the usual pressure foot might refuse to move ahead. You can use a walking foot for this.
Do not do anything that will stretch the fabric as it is handled during sewing. The pattern pieces would not even match if handled wrongly. The most stretch happens along armholes, shoulder seams, waistlines, necklines and zippers, so take care of those areas.
Necklines are usually bound. It is better than using facing.
Buttons and buttonholes may be difficult to sew because of the stretch. Choose fasteners like zippers.
What interfacing to use ?
Whatever you use it should have the same feel and drape of the knit you are using. You need to use the lightest weight fusible. Use a knit tricot (fusible ) or a stretch non-woven interfacing.
You can also use the self fabric as interfacing if the fabric has good stretch. Preshrink interfacing as you have preshrunk the knit fabric.
How to sew seams on knits ?
The best way to sew seams on knits is using a serger. The serger gives a nice stretchy stitch and finishes the fabric edges in one go. But if you do not have a serger, there are alternatives in your regular sewing machine.
Regular straight stitch doesnot work on knits because of the stretch inherent in its structure. It will just snap /break. You can use a long narrow zig zag stitch or elastic/stretch stitch (triple stretch stitch) which will similarly tolerate the stretchiness of knits. Use a small zig zag stitch of 2.5 mm length and .7/1.5/2 mm width (experiment). Use a 3 mm to 3.5 mm stitch on looser knits.
Test the zig zag stitch width on a fabric scrap of the same fabric before using on your final stitching. The stretch stitch is stronger than zig zag stitch so use that if you have a choice.
On some stable knits you can use a straight stitch. Make double stitching lines 1/4 inches apart.
The seams of shoulder, waist, neckline etc may need to be stabilised otherwise it will stretch out of shape.
What to do with fabric edges ?
Knit edges can be left as it is as the edges would not fray as it does for woven fabrics. But the problem is that fabric edges do curl. So you may want to finish the seam allowance edges for a neat look.
You can also bind the edges with bias binding strips for a very neat look. You can read this tutorial to bind a knit neckline with a store bought seam binding tape for a neat look.
You can also use a overacasting stitch on the edges.
How to sew hems on knit garments ?
This is assuming again that you do not have a serger. Sewing with serger is the best way to hem knits too – no question about it.
Hang the garment for a day before sewing the hem.
You can sew hems with a tight zig zag stitch / elastic stitch. Otherwise you can use a twin needle 2.5/75 or 4/100
Twin needle used along with a longer stitch length of 3 or higher will make a hem similar to a coverstitch hem. After folding the fabric just sew from the top with the longer stitch length and twin needles on. Checkout the post on twin needle stitching for more details.
Fold the hem and press. Thread the bobbin without much tension. Thread the twin needles. Adjust the stitch length to 2.5 to 3 mm. Sew without stretching the fabric. Sew from the top and you will get a coverstitch like stitch on the back.
You can stabilise hems with a light weight knit fusible interfacing to ensure that the fabric do not curl.
You can also use a rolled hemmer foot to make a lettuce edge, if you like this effect. Learn how to make a lettuce hem here. It is a very pretty hem edge for kids’s clothes.
How to prevent stretching of edges on knits?
Some knits are very unstable like a thin looseley knit jersey fabric. You will have to stabilize necklines because of the flexible nature of these fabrics.
You can stabilize with bias fusible tape or a fabric strip of the same fabric or twill tape or nylon tape. You can also staystitch the neckline and cut edges to make them less stretchy. Zipper plackets, button hole stands all have to be stabilized in a similar way.