Buttonhole Problems: From Gaps to Total Refusal

A buttonhole is the last thing a garment asks of a sewing machine. The zipper is set, the collar is pressed, the hem is done, and then a handful of tiny stitches decide whether the whole project gets worn or gets folded into the mending pile.

That timing feels almost deliberate on the bench. A buttonhole asks a machine to change stitch width, thread tension, fabric density, and feed direction inside a space smaller than a fingernail, all while the sewist holds their breath over a finished shirt front.

Most buttonhole failures are not mysterious once you have seen them a few hundred times. They repeat in the same half dozen patterns, and every one has a specific, fixable cause. Work through this list in order and the machine that just embarrassed you on a blouse front will earn its keep again.

How the One Step Lever Actually Reads Your Fabric

A one step buttonhole foot holds the button in a sliding tray at the back. The machine measures that button, then uses the small buttonhole lever near the needle bar to track the foot’s position as it sews forward for the left side, across the bartack, back for the right side, and closes with the top bartack. The lever is the machine’s ruler for the whole operation.

Pull it straight down until it drops fully behind the little metal post at the back of the foot shank, not just partway. A gap of even 2 mm there is enough to lose the count, and the machine either loses track of where the cycle should end or never starts tracking at all.

On computerized machines the mechanism is usually an optical sensor built into the foot rather than a manual lever, but the principle matches: something has to read fabric position accurately, and lint, thread scraps, or a foot that is not fully seated in its clip will throw that reading off before the first stitch.

The Machine Sews One Side, Then Stops or Loops

Two complaints trace back to the same loose lever. The first is a machine that sews the left column and the bottom bartack, then simply halts, as if the buttonhole were finished at half length. The second is a machine that sews the same column over and over, looping, without ever swinging into the bartack.

Both point at the lever not seating behind its bracket. Raise the presser foot, look at the small metal finger below the needle bar, and pull the lever firmly toward the back of the machine until it clicks past the post on the foot. Test on a folded scrap before returning to the garment.

Thick fabric causes the identical fault on a machine that is otherwise perfectly healthy. A lapel with three or four layers, or a padded placket, can lift the foot just enough that the lever cannot drop fully behind its post, and the machine reads that as no lever at all.

One Side Denser Than the Other

Fabric does not always feed the same way in both directions. Nap, grain, and layered interfacing edges can make the left column of a buttonhole look tight and even while the right column looks loose and thin, even though the machine never changed a setting.

Fuse a scrap of woven interfacing behind the buttonhole site, even on fabric that already carries interfacing elsewhere in the garment. The extra layer gives the feed dogs something consistent to grip in both directions.

Add a strip of tear away or wash away stabilizer directly under the stitching for anything lightweight, a cotton lawn or a rayon blouse fabric especially. Slow the pedal down as well. A satin stitch sewn at full speed outruns uneven feeding; sewn at a third of the usual speed, the feed dogs and needle stay in sync on both passes.

Gaps and Skipped Stitches Near the Ends

A buttonhole placed near a facing edge, a waistband seam, or a thick side seam crosses a bump on its way through the fabric. The presser foot tilts for an instant as it climbs that bump, the needle deflects sideways, and the result is a gap or a skipped stitch right at the point where the seam sits.

A folded scrap of fabric or a business card, tucked behind or beside the foot to level it while it crosses the bump, keeps the needle entering straight through that section. Quilters call the tool a hump jumper, and a stack of two or three fabric scraps taped together works just as well.

Check the needle too. A dull or slightly bent point deflects far more easily on any bump, even a small one. Fresh 75/11 or 80/12 needles handle buttonhole density best, and a needle that has already sewn a full garment’s worth of seams is not fresh anymore.

When the design allows it, moving the buttonhole a half inch away from the seam junction solves the problem before it starts, no leveling tool required.

A Keyhole or Bartack That Tangles Into a Knot

The bartack, or the round eyelet at the end of a keyhole buttonhole cut for a coat button, packs more stitches into less space than anywhere else on the garment. Top tension set for ordinary sewing, a 4 or a 5 on most dials, is too tight for that density, and it pulls the bobbin thread up through the fabric until the stitches bunch into a small knot.

Drop top tension to 2 or 3 specifically for buttonhole stitching, then test on the real fabric sandwich before cutting anything on the garment. The satin stitch should lie flat with both threads meeting at the middle of the fabric, not visibly pulling toward the top.

If the tangle persists after the tension adjustment, switch to a lighter 40 weight embroidery or rayon thread for the buttonhole itself. The reduced bulk often finishes what the tension change started, especially on a keyhole eyelet where the stitches converge into a tight circle.

Four Step Buttonholes That Do Not Match

Mechanical machines without an automatic foot ask the sewist to select each of the four stages by hand: the left column, the bottom bartack, the right column, and the top bartack. Length depends entirely on judging distance by eye, which explains why the second and third buttonholes on a shirt rarely match the first.

Mark both ends of every buttonhole with tailor’s chalk before threading a single stitch, then count the stitches the machine takes to cover that distance on the first buttonhole. Match that count, not a guess, on every buttonhole after it.

A clear plastic buttonhole gauge, priced around 5 to 8 USD, prints length markings directly onto a ruler that lines up against the fabric edge. It removes the guessing entirely and is worth owning if a garment needs more than two buttonholes.

Corded Buttonholes for Knits and Stretch Wovens

A buttonhole sewn into a knit cardigan or a stretch woven blouse stretches a little wider every time a button forces its way through, and after a season of wear the hole no longer holds the button snug. Cording solves it.

Hook a length of pearl cotton, size 8, or buttonhole twist over the small spur at the back of the buttonhole foot, with both tails held forward under the foot. Stitch the buttonhole as usual, and the satin stitch encloses the cord along both long sides as it sews.

Pull the two cord ends snug once stitching finishes, which draws the hole in slightly and firms up the edge. Thread each tail onto a hand needle and bury it between the fabric layers rather than trimming it flush. A corded buttonhole holds its shape through years of buttoning, not just the first fitting.

Before You Cut: Setup Checklist and Fault Finder

The Pre-Buttonhole Checklist

• Fuse a scrap of woven interfacing behind every buttonhole site, even on fabric that already carries interfacing elsewhere.
• Load a fresh 75/11 or 80/12 needle; dense satin stitching dulls a point faster than ordinary seams.
• Build a real fabric sandwich, outer fabric, interfacing, and facing, and sew one full test buttonhole on it before touching the garment.
• Match the button to the foot’s holder exactly, or set the length by hand if the machine has no automatic foot.
• Set top tension to 2 or 3 for the satin stitch and check width and length against the machine manual.
• Confirm the buttonhole lever drops fully behind its bracket before the first stitch.

Buttonhole Fault Finder

Buttonholes reward patience more than any other stitch on the machine. A minute spent on a test swatch, cut from the same fabric and interfacing sandwich as the real garment, catches most of these faults before they land on a finished placket.

When a hole still comes out wrong after working through the checklist, the cause is almost always sitting in that list already, not buried somewhere deeper in the machine. Go down it in order rather than guessing at parts to replace.

Open the finished buttonhole with a seam ripper and a pin set as a stopper, never scissors alone, and the garment that nearly went back to the mending pile earns its buttons instead.

Frequently asked questions

Why does my one step buttonhole machine sew the first side and then stop?

The buttonhole lever almost always has not dropped fully behind the bracket on the foot. Raise the presser foot, pull the lever straight down until it clicks past the metal post, and test on a folded scrap. Thick fabric under the foot can cause the identical fault on an otherwise healthy machine.

Why are the two sides of my buttonhole different widths or densities?

Fabric usually feeds slightly differently in each direction because of grain, nap, or an uneven interfacing edge. Fuse interfacing behind the whole buttonhole site, add a strip of tear away stabilizer underneath, and slow the pedal to about a third of normal speed.

Why does my buttonhole have gaps or skipped stitches near one end?

The needle is likely deflecting as the presser foot climbs a seam bump close to that end, common near a facing edge or waistband seam. Level the foot with a folded fabric scrap while crossing the bump, and check that the needle is a fresh 75/11 or 80/12.

Why does the bartack at the end of my buttonhole turn into a tangled knot?

Top tension set for regular sewing, usually 4 or 5, is too tight for the dense stitching in a bartack or keyhole eyelet. Drop it to 2 or 3 specifically for buttonholes and test on the actual fabric sandwich before cutting the garment.

How do I sew a corded buttonhole on a knit fabric?

Hook a length of size 8 pearl cotton or buttonhole twist over the spur at the back of the buttonhole foot, holding both tails forward under the foot. Stitch as normal so the satin stitch covers the cord, then pull the ends snug and bury them with a hand needle.