How to Sew a Blanket Stitch

What the loop actually does: the structure behind the stitch

Every stitch in a blanket stitch does two jobs at once. The vertical bar that runs from the marked line out to the edge is the part that covers and protects the raw edge, and the loop at the outer end is what ties the row together. Because the needle goes down on the marked line and comes up on the outer edge, the bar is anchored in solid fabric at one end and casts freely over the very edge at the other — no part of the stitch is sewn into thin air.

The loop is the load-bearing part. When you pass the needle through the thread left at the edge before pulling tight, the new loop traps the previous loop's thread. Pull on one stitch and the force travels sideways along the row instead of opening a hole, which is why a blanket-stitched edge does not unravel the way a single row of running stitch does. That is also why the very first loop depends on the small backstitch from step 2 — there is no earlier loop yet to take the strain.

The 5 to 8 mm depth is not arbitrary. It is the seam allowance: the bar has to span from the marked line to the outer edge, so the deeper you set the line, the longer and more exposed each bar becomes. Set the line too close to the edge and the loops crowd the very edge where the fabric is weakest and can tear out under use; set it deeper than the allowance on a narrow piece and the bars run past the fabric into nothing.

Common mistakes, how to spot them and how to fix them

Standing-up loops are the most common fault and they always mean the same thing: too much tension. The loops should lie flat against the edge, and if they curl upward like a row of little arches you are pulling each loop tight before it has settled into place. Ease the tension over the next few stitches and compare — the difference shows within three or four stitches and tells you exactly how light your hand should be.

Sagging, uneven loops are the opposite problem, and they are usually caused by passing the needle through the loop loosely and then pulling the bar, so the loop never closes. The fix is in the order of the motion: pass the needle through the loop first, then tighten the loop, and only then move on to the next stitch. Do not tighten the bar and the loop in two separate pulls.

A drifting edge is harder to catch while you work, because you are watching the loops rather than the bars. Every few stitches, look along the marked line instead of at the edge: if the bottoms of the bars wander above and below that line, the row will read as wavy even when the spacing between stitches is perfect. Mark the line more visibly, or run a strip of low-tack tape along it as a hard stop for the needle.

Do not try to correct a bad stretch in place. Unpick back to the last stitch that sits correctly — the loop structure comes apart easily in reverse — and rework from there. Local easing, sliding the needle under a loop and lifting gently, can buy you a millimetre, but it will not rescue a whole row, and a half-corrected row is more obvious than one that was restarted.

Choosing thread, needle and fabric, and what a swap changes

Thread choice changes the look more than any other decision. All-purpose thread gives a flat, quiet edge that blends into woven fabric; a single strand of embroidery floss or a doubled thread stands proud of the edge and makes the loops read as a deliberate decorative border, which is what you want on felt and wool. If you use floss, check it against your needle first — an eye too small for the strand frays and shreds the floss as you work, and the damage shows up mid-row rather than at the start.

Needle choice follows the fabric. Felt and fleece are dense rather than tightly woven, so a sharp embroidery or sharps needle slips between the fibres; a blunt needle on felt tends to punch and stretch them instead of parting them, which distorts the edge you are trying to finish. On heavyweight woven fabric the same sharp needle is what lets you place each bar exactly on the marked line rather than a thread or two off it.

Marking is the swap most people get wrong. On felt and fleece, chalk and water-soluble pen both sit on the surface and can leave a ghost behind, so work by eye and hold the depth consistent instead. On smooth, dark or heavyweight woven fabric the marked line is the only reliable guide for the bottoms of the bars, so mark it, and re-mark as it fades rather than estimating.

Pins versus clips matters right at the edge itself. Pins set close to the edge are easy to catch with the needle as you come up on the outer edge, and catching one drags the loop out of shape; clips hold the layers without putting metal where the needle has to travel. That is why clips are worth reaching for on fleece and on any join where you are stitching through two layers at once.

Variations: spacing, thread weight and skill level

Spacing is the main dial you have. Within the 5 to 8 mm range, the narrow end gives a dense, solid-looking edge that suits small applique shapes and toy parts, where each bar has only a short run of edge to cover. The wider end gives an airier, more open border that suits a long straight edge such as a blanket or the top of a bag, and it also works up noticeably faster because there are fewer stitches to place.

Thread weight can be varied to match. For a fine, quiet edge on lightweight felt, work with a single strand of all-purpose thread at the narrow end of the spacing range — the stitch becomes a neat finish rather than a feature. For a chunky, graphic look, use the doubled thread or the floss from the tips and open the spacing slightly, so the thicker loop has room to sit flat instead of crowding the loop beside it.

Worked with the needle passed through the same loop twice, the stitch becomes a crossed or closed blanket stitch: the loops overlap and fill the edge almost solidly. It is the same motion as the basic stitch, repeated into the live loop before tightening, and it is a natural next step once your plain row is even. It uses more thread per centimetre of edge, so cut a longer length than the usual 45 cm.

If you are new to the stitch, work a short strip of scrap felt first — not to practise the look, but to find the tension your hands settle into naturally, and then reproduce that tension on the real piece. If you are already comfortable with it, the natural progression on this project is joining two pieces of felt: the identical motion, but now both layers have to be caught to the same depth, which is the part that takes practice.

Finishing and care so the edge lasts

The finish is where a good row is either preserved or ruined. Locking with two small stitches on the wrong side and running the tail under the edge works precisely because of the 5 to 8 mm depth: there is a channel of fabric between the marked line and the raw edge, and a tail threaded through that channel disappears completely. Push the tail through in the direction the stitches travel, not back against them, so it cannot work loose.

Press from the reverse and press lightly. Direct heat on the loops flattens the very feature you worked to create, and embroidery floss scorches and glazes faster than sewing thread; on felt, a hot iron can also crush the fibre and leave a shine. Turn the piece over, use a little steam if the fabric tolerates it, and let it cool flat before you judge the edge.

For washing, treat the edge as the fragile part. Hand wash in cool water with a mild soap, squeeze the water out rather than wringing — twisting is what distorts loops and pulls the bars out of line — then roll the piece in a towel to blot it and dry it flat. Felt and fleece are the least forgiving here: a piece joined with a blanket stitch seam should not go through a machine wash, because the agitation both mats the felt and abrades the exposed loops.

If a loop later snags — a soft toy after a wash, a bag catching on something — do not cut it. Work the loop back into shape with a blunt needle, easing the slack along the row towards the nearest locking stitch, then secure it with a tiny stitch on the wrong side. Because the loops interlock with one another, a single snagged loop usually redistributes its slack rather than breaking, and the row stays intact.