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Seaming
Mattress stitch, whipstitch, backstitch and crocheted seams: which to use where on a garment, how to match rows, and how to make a seam disappear.
By The StudioPublished Aug 15, 20265 min read
A garment worked in pieces lives or dies by its seams. A good seam is flat, invisible from the front, and just as stretchy as the fabric around it. A bad one is a ridge that shows through a shirt and puckers when worn. The skill is small, the tools are a tapestry needle and patience, and the difference in the finished garment is enormous.
Preparation
- Block the pieces first, to the schematic measurements. Flat, equal pieces seam easily.
- Use the project yarn for the seam if it is smooth and strong. Use a matching thinner yarn or a smooth cotton for fuzzy, bulky or weak yarns.
- Pin or clip the pieces together with the ends matched and the middle matched, then between, so the seam is eased evenly if the pieces differ slightly.
- Seam on a table, not in your lap, with the pieces lying flat and the light on the edge.
Mattress stitch
The invisible seam for side seams and sleeve seams, joining row ends to row ends. Lay the two pieces flat, right sides up, edges touching. With the needle, pick up the bar between the first and second stitch on one piece, then the matching bar on the other, and go back and forth, one row on each side, without pulling tight. After every 5 cm, pull the yarn gently and the seam closes like a zip, with the edge stitches folding inside. From the front, the two pieces become one.
- 1Anchor the yarn at the bottom with a figure eight through both pieces.
- 2Insert the needle under the horizontal bar between the edge stitch and the next stitch on the right piece, one row up.
- 3Do the same on the left piece, at the same row.
- 4Repeat, alternating sides, matching row for row. Every few centimeters, snug the yarn until the seam closes and lies flat, then continue.If one piece has more rows than the other, ease by occasionally picking up two bars on the longer side.
Whipstitch
For shoulder seams and anywhere stitch tops meet stitch tops, whipstitch through the back loops with the pieces right sides together. Fast and flat, and the front loops make a tidy line on the right side. It is less invisible than mattress stitch but it is the right choice for a horizontal seam that will be under a little strain.
Backstitch
The strong seam. Right sides together, sew a running stitch that goes forward two and back one, so every stitch overlaps the last. It makes a firm, slightly bulky seam with no stretch, ideal for bag seams, the join of a strap, or a shoulder seam that has to carry the weight of a heavy sweater. Not for anywhere that needs to drape.
Crocheted seams
Slip stitch or single crochet through both layers, right sides together, with a hook. Faster than sewing and very strong, but the seam is a ridge on the inside and it has no give. Use it on the inside of bags and baskets, for joining blanket strips, and for shoulders of heavy garments. Worked with wrong sides together in single crochet it becomes a visible, decorative seam, which some designs use on purpose at the outside of a raglan or a yoke.
Which seam where
| Seam | Stitch | Why |
|---|---|---|
| Side and sleeve seams | Mattress stitch | Invisible, stretchy |
| Shoulder seams | Whipstitch or backstitch | Flat and holds the sleeve weight |
| Setting in a sleeve | Mattress or whipstitch | Follows the curve with pins first |
| Bag and basket seams | Slip stitch or backstitch | Strong, no stretch |
| Blanket strips | Whipstitch or slip stitch | Fast over long edges |
| Toy parts | Whipstitch through both layers | Firm, hides in dense fabric |
Order of seaming a garment
Shoulders first, so the body hangs as one piece. Then set the sleeves into the armholes while the body is flat. Then the side and sleeve seams in one pass from hem to cuff. Then the neckband, worked around the joined neck opening. Seaming in this order keeps every seam accessible and flat while you work it. The Sundial Tee has only four seams and is a gentle place to practice mattress stitch in an open fabric where it is easy to see the bars.
Finish by steaming or wet blocking the seams lightly once the garment is assembled. They flatten, the yarn settles, and a slightly uneven seam becomes a good one.
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