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A Summary of Seaming Techniques & Joining Edges

by Sharyn Anhalt December 13, 2014

A Summary of Seaming Techniques & Joining Edges

Just as there are many ways of joining yarn, there are many ways of joining edges, or seaming. With a few basic sewing skills in your arsenal, you can master the challenge of seaming neatly and professionally! Again, I offer a few basic rules:

Leave long ends when binding off – wasn’t that a rule for weaving in ends? Yes! Always leave a long end when securing a bind off so you have options for seaming and weaving in ends. It’s much easier to sew a seam with an end than having to join a new piece of yarn.
Use the same yarn for seaming as you did for knitting – provided it is strong and not too bulky or fuzzy. Try pulling on a length of yarn to test the strength, and if it pulls apart easily it should not be used for seams. Because of the twists and turns of knit fabric, softly spun yarn is strong in knitting but can be unsuitable for sewing. Likewise, if you’re knitting with super bulky yarn, a seam sewn with super bulky yarn will be… well, super bulky. It’s best to use a lighter yarn in a matching color. Be sure that your seaming yarn has the same wash-ability as your garment yarn.
In general, use a length of yarn shorter than 18 inches – continually pulling a long length of yarn through your knitting will abrade and weaken it. You can probably use a longer length with a super smooth yarn, such as mercerized cotton.
If your pattern gives a sequence for sewing together the garment, follow it. Usually there is a reason to sew things together in a certain order even if it isn’t explained in the pattern.
Consider blocking your pieces before sewing them together. Trust me, it will be much easier to line up edges and stitches.
Pin or baste the pieces together before seaming, to ensure that they line up. If you baste the pieces together (with a loose running stitch) you can potentially try the garment on and adjust the seaming for any fit issues.
This may go without saying, but use a yarn needle not a sewing needle.

Through the Woods Hooded Cowl, ready for the front plackets to be seamed

Through the Wood Hooded Cowl, ready to attach the front button plackets. The plackets are knit separately and seamed onto the hood. Knitting them separately at a tight gauge with a smaller needle provides a sturdier fabric to support the buttons.

Now that we know the rules, how exactly do we sew the seam? There are several methods of course – the pattern instructions may tell you which one to use, you may have a personal preference, or your experience will tell you that one is more appropriate for the garment than another.

There are many, many online video tutorials on how to accomplish the stitches for these seams, or invest in a good reference book on knitting techniques. A good place to start is this handy tutorial from Vogue Knitting, or at KnitPurlHunter.

The following is a brief summary of stitches:

Mattress Stitch or Invisible Seam – most typically used for joining two pieces of vertical stockinette stitch knitting, but it can also be used for joining vertical stitches to horizontal, garter stitch to garter stitch, and many more. There are numerous videos and tutorials on the internet to demonstrate all these variations. The two edges are joined a half stitch in from the edges while working from the right side of your knitting, and when done properly the seaming thread “disappears” into the seam allowance. This is the most versatile seam, since it has little bulk and allows the knit fabric to drape.

Whipstitch – generally used when you have tightly knit edges that need to be held together securely. This creates a strong but bulky seam, so it’s usually used for utilitarian items like handbags or pillows. Usually worked with the wrong sides facing each other, the yarn is pulled through the two layers of knitting, over the seam edge, and back through the two layers. It can also be worked from the right side in a coordinating color for a decorative finish.

Backstitch – this is a strong seam that is ideal for curved seams such as armholes, or where you need to ease in fullness. This stitch is worked with right sides together, inserting the needle two stitches ahead, then one stitch back. You are essentially working a circular motion with your seaming yarn, creating an elastic seam. Give a gentle tug every few stitches to smooth out puckers.

Slip Stitch Crochet – no needle or sewing required, you simply crochet two pieces of knitting together with a slipstitch. This definitely produces a seam with more bulk, but it’s super easy to work – and super easy to remove if you’ve made a mistake.

Other Ways of Joining Two Pieces of Knitting

A couple methods of joining knitting that are not truly seaming, but useful to know that they may be used to join pieces of knitting:

Kitchener - grafting together two edges of live knit stitches. Typically used at the toe of a sock.

Three Needle Bind Off – joining two edges of knitting together while binding off two sets of live knit stitches. Worked by knitting two stitches together from two needles held together, then proceeding with the usual bind off of one stitch pulled over another.