Stretched-out seams, skipped stitches and knits that expand like crazy? We all have these issues when sewing knits. But don’t worry, if you follow these tips you will avoid common problems when working with stretchy fabrics.
1. Picking the wrong fabric
Not all knit fabrics are created equal. Things like stretch, recovery, fabric weight and thickness will all affect the result. For instance, don’t use a soft 4-way stretch knit when making more constructed garments like a knit jacket or pants with detailing such as pockets.
And if you are sewing a very tight-fitting garment and need to move around a lot, such as leggings. Then pick a fabric that has both crosswise and lengthwise stretch.
Guidelines for picking knit fabrics
- Tight-fitting activewear: Use Lycra-based fabric with both crosswise and lengthwise stretch (4-way stretch).
- Jackets and dressier pants: Use a stable knit, ideally with minimal lengthwise stretch (i.e. sweatshirt fabric, French terry and Ponte di Roma).
- Body-con, clinging dresses, leggings and skirts: Use a slightly heavier knit fabric with great crosswise stretch and great recovery. If the fabric is too thin, every line shows through the fabric, including your underwear. Plus you won’t get that nice silhouette if the fabric grows on the body and loses its shape.
Want more guidelines? Check out our book Fit for Knits where we have an extensive guide to every type of knit fabric and suitable projects.
2. Cutting knit fabrics off-grain
Cutting knit fabrics is quite different from wovens. Finding the grainline and cutting straight is often trickier for instance, so you need to use a different approach.
Follow the rib, not the “selvedge”
There is no selvedge on knits, so do not assume that the fabric has been cut straight. This means you can’t measure the grainline from the fabric edge the way you do with wovens. Instead, look for the vertical formation (rib) on the fabric and align the grainline with that line.
If you are cutting on the fold, align the fold along a vertical rib and place the pattern piece on the folded edge.
Cut the pattern pieces as single layers
Are you using striped, patterned or soft, supple knits? Then it’s usually better to cut the pieces one at a time on a single layer of fabric. Cutting these materials on the fold is often tricky as it’s almost impossible to perfectly align both layers without having the fabric being off-grain.
Want to learn more tips on how to cut knits? Check out my guide Cutting Knit Fabrics: 8 Essential Tips For Success.
3. Using the wrong stitches
You need to pick a stitch that has great stretch and is durable. A regular straight seam won’t cut it. Instead, pick a stitch that is made for sewing stretchy fabrics.
Sewing machine stitches
Side seams
- Stretch overlock seam (check your manual)
- Narrow zigzag stitch
Hemming
- Twin-needle (Tutorial)
- Zigzag stitch
- Blind-hem stitch (Tutorial)
- Picot-stitch or lettuce edge (a bit more advanced)
Serger stitches
Side seams
- 3- and 4-thread overlock
- Flatlock (more advanced, 3-thread flatlock tutorial)
Hemming
- Lettuce edge
- Blind-hem
- 3-thread overlock
- Flatlock
Coverstitch
Hemming
- 2-needle coverstitch (Coverstitch hemming tutorial)
- 3-needle coverstitch
- 5-thread top cover (available on some machines)
Grab my free guide to stitches for knits
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4. Using the wrong needles
The wrong needles can cause skipped stitches and holes in the fabric when sewing knits. In general, always use a ballpoint needle designed for sewing knit fabrics.
I highly recommend both the Schmetz/Euro Needles and Organ brands (Amazon affiliate links). They make knit needles for both sewing machines, sergers and coverstitch machines. To learn more about the different types of machine knit needles and their uses check out my Guide to sewing machine needles for knits.
5. Not stabilising the fabric
Sometimes the stretch in knits can cause some troubles. Especially if are sewing details such as zippers, pockets and collars. Otherwise, you might end up with a stretched-out, wobbly mess!
Examples of when you need to stabilise knits
- Pockets
- Necklines
- Zippers
- Shoulder seams (Tutorial)
- Facings (Tutorial)
- Buttonholes and eyelets (Tutorial)
I recommend using stretch fusible interfacing, to learn more check out my guide to using fusible interfacings for knit fabrics.
6. Not pressing as you sew
Just like with wovens, press each seam before you sew the next one.
Tips for pressing knits
- Use lower heat than usual (always test on a fabric scrap)
- Iron from the reverse side first
- When pressing from the right side, use a pressing cloth to protect the fabric
- Press side seams to the back
- Press shoulder seams to the back
- Fold and press the hem on the sleeve before sewing the side seams. It makes it much easier.
- Press the neckband fold before attaching it to the neckline (Neckband tutorial).
So these were some common mistakes when sewing knits. And trust me, I’ve done them all myself! I hope you found this post useful and please share some mistakes you’ve made in the comments so that we can all learn from each other!
