A button comes off a coat and the thread is still there, a short tuft of it standing up out of the cloth. Another button on the same coat sits at a slight angle with a dimple in the fabric around it. Neither of those is a thread that simply wore out. Both are about the small gap of thread between the button and the cloth it is sewn to, a gap that is put there on purpose and sized for the job. When it is the wrong length, or when it goes, the whole front of the garment tells you about it.
The Gap Is Deliberate
On a well made garment, a flat button does not sit against the cloth. It stands a little way off it, held up by a short column of the same thread that attaches it, usually wrapped around on itself to make a neat stalk. That column is the shank, and it is as much a part of the construction as the button is.
Some buttons have the gap built into them. A metal blazer button with a loop on the back, or a plastic button with a post formed on the back, carries its own shank and is sewn through that loop, so the body of the button is already held clear of the fabric. Those are called shank buttons and they need nothing extra.
A plain two hole or four hole button has no such thing. Sewn tight, it lies flat against the cloth with its holes pulled down hard, and the thread passing through them has no slack at all. Whatever gap is needed has to be created by the person sewing it, by holding the button up off the surface while the stitches are made.
That is the whole difference between a button that stays put and one that does not. It is not the number of stitches and it is not the strength of the thread. It is whether there is a space under the button big enough for the layer that has to pass through it.
Why The Buttonhole Layer Needs Room
A fastening is two pieces of cloth brought into the same plane. The button sits on one side, the buttonhole is cut in the other, and when the garment is closed the buttonhole side has to lie between the button and the cloth that button is sewn to. That layer needs somewhere to be.
With a shank, it slides into the gap and lies flat, and the button rests on top of it without squeezing anything. Without a shank there is no gap, so the buttonhole layer forces its way into a space that does not exist. The cloth has to deform to make room, and it does so by puckering around the hole.
That deformation does not stay local. A placket is a continuous strip, so strain introduced at one button pulls on the cloth above and below it. The usual result is the gaping you see between fastenings on a tight shirt front, along with buttons that sit at odd angles because each one is being pushed sideways by the cloth it is trapping.
The shank also lets the button pivot. A button on a short thread stalk can tilt to follow the fabric as the wearer moves, which keeps the load spread across the stitches. A button sewn flat cannot tilt, so every movement loads one edge of the hole at a time, and that is how a button eventually pulls a hole through a thin placket.
Length Has To Match The Thickness
The rule behind the length is simple. The gap should be about as deep as the layer that will sit in it, which means the shank length is set by the garment rather than by habit. Measure the buttonhole side with the facing, the interfacing and anything else stacked up in it, and that thickness is the target.
On a dress shirt the placket is two layers of poplin and a strip of interfacing, so the gap needed is a fraction of an inch and the stalk is almost invisible. That is why shirt buttons look flat even when they are not. There is a shank there. It is just short enough that nobody notices it.
On a winter coat the arithmetic is different. The buttonhole side may carry a heavy shell, a layer of interfacing, an interlining and a lining, and a quarter of an inch of stacked thickness is not unusual. A stalk sized for a shirt is simply too short on a coat like that, and the symptom is the dimple in the fabric around the button.
A heavy coat usually has one more thing, a small flat button sewn on the inside directly behind the outer one, called a stay button. The stitches pass through both, so the load from the outer button is carried by the inner one as well, and neither of them has to pull on the shell cloth on its own.
Why It Fails First In A Wash
Everything else on a garment is cloth protected by cloth. A shank is exposed thread standing clear of the surface with nothing around it, which makes it the most vulnerable thread on the whole piece. In a drum it rubs directly against other garments, against the drum wall and against itself.
Thread is strong in tension and weak against abrasion. A few strands of polyester or cotton will hold many pounds in a straight pull and fray away against a rough edge. Nothing in a wash pulls hard enough to break a stalk in tension. What the wash does instead is sand it, one pass at a time.
The button works as a lever against it too. A button is a rigid disc on a short stalk, so water drag and tumbling apply a twisting force at the base rather than a straight pull. Twisting flexes the same few strands back and forth, and flexed fiber abrades against itself at the point where it bends.
This is why a wrapped stalk lasts so much longer than an unwrapped one. Wrapping puts a sacrificial layer of thread around the load bearing strands, so the abrasion lands on the wrapping instead. It is also why a thread shank on an old coat often looks fuzzy and slightly longer than it used to be. The wrapping has gone and the core is unwinding.
Reading The Failure On The Garment
The remains tell you what happened. A button gone with a tuft of thread still standing in the cloth means the stalk was cut through by abrasion, with the stitches in the fabric untouched. A button gone cleanly, leaving a small hole or a pucker behind, means the stitches pulled out of the cloth, which is a different failure with a different cause.
A button that has gone loose while the thread still looks intact is a stalk that has lengthened. The wrapping has unwound and the strands have spread, so the gap is now deeper than it should be and the button flops. It will fail soon, and it is far easier to resecure while the thread is whole than after the button is gone.
A dimple in the cloth around a button that has never moved is the opposite problem, a stalk too short for what it has to hold. Nothing is going to break, but the garment front will sit badly for as long as it is fastened that way, and the puckered cloth will eventually hold a permanent crease.
For laundering, the useful habits are few. Fasten the garment before it goes in, so the placket cannot twist and the buttons cannot catch on anything. Keep heavy buttoned pieces in a mesh bag or run them on a gentle cycle, since the stalk is wearing whenever the drum is moving. And resecure anything loose before washing rather than after.
Thread Shank Wear In Tempe
Coats in Tempe spend most of the year in a closet and then get worn hard for a short stretch. That pattern is unkind to buttons. A coat that has hung untouched for months comes out with its thread stiff and dry, and dry thread abrades faster than thread that has stayed supple. The first few wearings are when buttons tend to go.
Dry indoor air is part of it. Cotton and polyester thread both hold a little moisture, and in very dry conditions they give it up, becoming slightly brittle and more prone to breaking apart under repeated flexing. Nothing about that is dramatic. It simply shortens the life of the most exposed thread on the garment, which is the one standing under the button.
Heavy coats are also awkward at home, because a coat needs room to move for water to reach through the layers. A packed drum presses buttons hard against the drum wall and against other garments. WaveMAX Tempe, at 222 E. Baseline Rd., has larger machines and gentle cycles, which is what a buttoned winter piece actually needs.
Gentler Cycles For Coats
A coat is mostly layers, and layers need water and room rather than agitation. A large drum lets a heavy piece turn over without being pressed against the wall, which is where exposed thread gets sanded down, and a gentle cycle keeps the twisting forces on every button stalk as low as they can reasonably be.
The machines at our self-service laundry on East Baseline Road give a heavy buttoned coat enough room to turn over on its own, so the exposed thread under each button is not being ground against the drum wall, and the gentler cycles keep the twisting load low throughout.
Our machines and the store are cleaned daily.
Our wash-dry-fold service covers the everyday laundry.
For general guidance, The American Cleaning Institute publishes a fabric care guide that is a useful cross-check.
The short version
The small gap of thread between a flat button and the cloth is there so the buttonhole layer has somewhere to sit. Its depth should match the thickness of that layer, which is why a coat needs a longer one than a shirt. Because the stalk is exposed thread standing clear of the fabric, it wears by abrasion rather than by pulling, and a wrapped stalk lasts far longer. A loose button with sound thread means the stalk is going.
WaveMAX Tempe is at 222 E. Baseline Rd., easy to reach from Tempe and the surrounding area. If you have a load that will not fit at home, call us at 480-278-9685.