If you’re someone who only sews garments, you may not be exposed to a corner seam.
I was originally taught this technique when I enrolled in my first sewing class, which I didn’t take until I’d been sewing for over 12 years. So you can imagine my surprise that this 101 technique was so new and interesting, especially since I had made nothing that featured this detail up until that point.
Since then, I’ve had to sew a corner seam on a total of two garments.
Yes, you read that correctly. Two.
I suppose that’s why its an inherently important technique to learn. Sewing a corner seam may not happen often, but when it does, being prepared and knowing what you’re actually looking at is vital.
Before getting started
Be sure that your corners are clearly marked.
In the video and photos, I used markers to mark my corners, as well as about an 1.5in/3.8cm line along the seam line as a guide. While working on your real garment, please use tailor’s tacks, tailor’s chalk, or a water soluble marker to make sure your fashion fabric is kept in good shape! (I’ve also been known to use a pencil, but that’s just me!)
If you’re making a corner seam on a curve or as part of a princess seam (such as on McCall’s 7625)- make sure that your notches are clearly marked before beginning. If you’ve made any drastic changes along that seaplane, also be sure to rewalk your pattern pieces to be sure they line up.
Pin, with right sides together, one side of the corner seam, timestamp 3:05.
The most important part to remember when you’re pinning everything, is to match up the corner seam first, since that is the most important feature of this seam. You want to make sure that the corners overlap perfectly.
Baste part of the seam in place, up until the corner, just so things don’t wiggle about.
Clip the corner on the main fabric, timestamp 4:25.
Make a small, diagonal clip into the corner, up until the stitch line, but not through it. This will become the pivot point for your corner seam.
Sew the corner seam in place, timestamp 4:36.
Starting on the side of the corner seam you basted, sew up the leg of the seam until you reach the corner. As you approach the corner, go slowly, hand cranking the needle until the sewing needle is sitting right in the middle of the corner seam. Lift your presser foot, with the needle down.
Begin to pivot the base fabric, around the needle (timestamp 4:55), until the second side of the corner seam is in the sewing position. Take the time to be sure that there’s no fabric folded underneath in a weird way, and that you can continue stitching straight. Sew the second side of the leg.
Clip the corner of the insert fabric and press your seams open, timestamp 5:43.
For a straight corner seam, clipping the seams and pressing them open normally will suffice. For corner seams on a curve, evaluate which way would be more natural for the seam to sit, and press in that direction instead.
Sewing a corner seam definitely takes some practice.
Between learning it in my sewing class and actually practicing it for a garment, it was a minimum of ten times before I felt confident enough to sew a corner seam without a second thought.
However, taking the time to make a sample is invaluable. There’s nothing as awful as a giant birds nest hole in your fashion fabric, because somewhere in the process everything became a hot mess.
Always make a sample of a new technique you’re trying. Always make a sample of an old technique you haven’t done in a while.
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If you’ve set up a fabric swatch book, these sorts of samples are great to keep in your book (or even in a second book!), with a note attached to them about construction and what worked for you. I have a stack of samples myself, which I pull out and review if I need to use them, with my own hand written notes.
Handwriting your own process notes is just as important as making the sample. Only you will understand what worked for you!