Sewing with knitted fabrics can be freeing although it is occasionally frustrating. It is freeing because knits like Spandex are so forgiving and very little fitting is needed, and the seams don’t need finishing. It can be frustrating if you don’t use the right tools and techniques when working with them. This blog will give you an overview of how to sew with knits so that the frustration is lifted and you can be free to enjoy sewing these comfortable fabrics as much as you enjoy wearing them. (check out my previous blog for information on choosing fabric and laying out the pattern)
Ballpoint sewing machine needles are a must, especially when sewing through elastic.
Fine, long straight pins are much easier to work with and don’t stick to the fabric.
A machine with a zigzag stitch and/ or a serger is best. A coverstitch machine is sweet but not essential.
For cutting knits I prefer a cutting wheel, but have used serrated scissors in the past (before the Olfa wheel was introduced). Regular scissors don’t work well as the knit has a tendency to slip and stretch whereas; the serrated edge holds the fabric against the cutting blade.
Pattern weights make cutting out faster.
A toothed tracing wheel works better than the smooth blade as the fabric tends to be thick.
Beyond this list, you can use pretty much what you already have in your sewing room. Make sure your thread matches your fabric type and not just the colour, i.e. use polyester thread for synthetics.
The method: Set your stitch length at 3-4 mm. 3mm is best for most garment weights, but you’ll need longer stitches for heavy fabrics like fleece.
Adjust the tension for the weight of the fabric as you would for a woven. (Tension adjustments are unique to every machine, so follow your manual on this.) Always stretch as you sew with a straight stitch, even when basting. Play with this on sample pieces until you’re comfortable with how much you have to pull on the fabric to get a seam that gives, does not pucker and maintains its shape. You should have one hand behind the needle and one in front keeping a steady tension and allowing your machine to pull the fabric through. If the seam appears stretched, you have put too much tension on your fabric and there is too much thread in the seam to allow the knit to relax back to its original shape. If it puckers, you haven’t got enough tension on the fabric and the seam will break when you try to stretch it.
Once the fit is right, serge the seams to give a ¼” seam allowance and a stretchy seam. If you are using blanket fleece serging just adds more thread to the already bulky seam and you don’t really need to finish the seam allowance.
Pressing knits should be done carefully and as little as possible as the fabric can stretch out of shape if worked too hard – or melt if the iron is too hot! Very often finger pressing is sufficient while sewing, especially on Spandex. Use a warm iron and steam and just touch the tip of the iron if possible.
Use a stretchable iron-on interfacing if it is required. You will want to maintain the soft feel of the knit even in a collar or cuff, so choose the weight of the interfacing accordingly.
Heming can be done by machine with a zigzag hem stitch or top stitch, twin needle top stitching or by using a two or three needle coverstitch. The coverstitch is used on most ready-to-wear tops and dresses. Whichever method you choose, keep in mind that the hem needs to stretch.
I hope this short lesson helps you with your next project. As always your comments and questions are welcome.