What's Inside a Suit Jacket: Canvas, Chest Piece, Shoulder Pads and Interlinings

Open a well-made jacket and you see only the lining. Behind it sit half a dozen layers you never see: a springy canvas, a horsehair chest piece, a soft felt, shoulder padding, linen tapes and a felt under collar. Together they decide how the jacket drapes, how the lapel rolls, how the shoulder holds its line and how many years the jacket lasts. Each layer is described below, with what it does and how to tell whether a jacket has it.

What is the canvas in a suit jacket?

The canvas is the main interlining of the jacket front: a springy fabric woven from wool or cotton with goat hair or horsehair, known in the trade as hair canvas. It covers the front panel behind the outer fabric. Bend it and it pushes back, and that spring is what gives a canvassed chest its curve and a lapel its roll.

In a canvassed jacket the canvas floats. It is held to the outer fabric with loose basting stitches and fixed firmly only at the edges, the shoulder and the armhole. Because nothing is glued, the outer fabric hangs from the canvas instead of being stuck to it, and with body heat and wear the canvas slowly takes the shape of your chest. A half canvas jacket floats canvas through the chest and lapels and fuses the lower front; a full canvas jacket floats it from shoulder to hem.

For the full comparison of the three constructions, read fused vs half canvas vs full canvas.

What does the chest piece do?

The chest piece is a set of extra canvas layers, usually horsehair, shaped and stitched over the upper chest and into the shoulder on top of the main canvas. It fills the slight hollow below the collarbone and gives a clean, smooth line from the shoulder down over the chest. Horsehair is stiff and springy, so a chest piece holds that shape for years.

Its size and firmness set much of a jacket's character. A large, firm chest piece gives the full, built-up chest of traditional English tailoring. A small, light one, or none, gives the softer line of many Italian jackets. Many fused jackets also have a small sewn-in chest piece, which is why the pinch test should never be done on the chest alone.

Domette: the soft cover

Horsehair is coarse, and its ends can work through the outer fabric or prickle. A layer of domette, a soft, fluffy wool or cotton interlining, covers the chest piece to prevent this and to soften the feel of the chest. On some jackets a thin layer of felt or wadding does the same job.

What is inside the shoulders?

Two parts build the shoulder. The shoulder pad sits on top of the shoulder between the canvas and the lining. It is made from layers of cotton or wool wadding, sometimes with felt, and in cheaper jackets often from molded foam. It can be a thin sliver that only smooths the line or a thick pad that squares and widens it. The second part, the sleeve head roll, is a strip of wadding or felt sewn into the top of the armhole. It supports the top of the sleeve so it runs cleanly from the shoulder without collapsing into a dent.

How much of each a tailor uses decides the shoulder style, from the unpadded Neapolitan shoulder to the padded, roped English one. Our guide to suit shoulders explains each style and which builds it suits.

What holds the lapel and front edges in shape?

The edges of a jacket are where shape is most easily lost, so tailors reinforce them with tape, felt and stitching.

• Bridle tape. A narrow linen tape sewn along the roll line, the fold where the lapel turns back. The roll line runs on the bias of the fabric and would stretch without it; the tape holds it to length and keeps the lapel lying close to the chest instead of gaping.
• Edge tape. A linen or cotton tape run along the front edges and around the lapel, so the edges stay straight and crisp rather than stretching into waves.
• Under collar and collar canvas. The underside of the collar is usually melton, a dense felted wool, backed by a collar canvas and pad-stitched so the collar curves around the neck and sits against your shirt collar.
• Pad stitching. Rows of small diagonal stitches fix the lapel and under collar to the canvas in a curve. Done by hand, they give the lapel its lasting roll; see hand-sewn vs machine-sewn.

What are interlinings and fusing?

Interlining is any layer between the outer fabric and the lining. Canvas is one kind; fused interlining is another. Fusible interlining is a light fabric coated on one side with small dots of resin, which melt in a heated press and bond it to the back of the outer fabric. Fused fronts are faster and cheaper to make, and modern fusing is far better than it was, but the front stays flatter, the lapel tends to lie flat, and if the glue fails it shows as bubbling.

Even good canvassed jackets use small pieces of interlining in places that need stability rather than shape, such as the pocket openings, the facings and often the hems of the body and sleeves, so the edges fold crisply. Their presence does not make a jacket fused. What matters is what holds the main front panel.

Unstructured jackets

An unstructured or deconstructed jacket leaves most of these layers out: little or no canvas, no chest piece, a thin pad or none, and often only a half lining. It is light, soft and cool, ideal for linen and cotton jackets in summer; see suit fabric for hot weather. The trade-off is that the fabric alone holds the shape, so the chest is softer and the jacket creases more easily. It is a different style, not a cheaper version of a canvassed jacket.

What does the lining do?

The lining is the last layer and the only one you see. It lets the jacket slide on and off, covers the canvas, padding and seams, absorbs some moisture and adds a little warmth. Good tailors use cupro, often sold under the Bemberg name, because it breathes and resists static; viscose is close behind; polyester is cheap but does not breathe; silk is luxurious but fragile. A well-cut lining has a pleat down the center back and a fold of spare length at the hem, so it never pulls on the outer fabric.

How much of the jacket is lined matters as much as the material. Full linings suit business suits and winter weights; half linings, which leave much of the back open, suit summer jackets. Sleeves are lined in almost every jacket so your arms slide in easily. Our guide to suit linings compares the materials in detail.

Pockets and pocketing

Behind every pocket opening hangs a bag of strong cotton twill, often called silesia, because pocket bags take far more wear than the lining. Most jackets have an inside breast pocket on each side, set where the facing meets the lining, and some add a smaller pen or card pocket below. Whatever you carry hangs between the layers, so heavy contents drag on the front of the jacket.

How do the inner layers affect drape and longevity?

Drape is how the jacket hangs, and the inner layers decide it. A floating canvas lets the outer fabric fall freely and curve over the chest and hips. Glued interlining makes the fabric and interlining act as one stiffer sheet, so the front hangs flatter. A firm chest piece and pad give a clean, upright line; light ones let the jacket follow the body.

Longevity follows the same logic. A canvassed front has no glue to fail and can be reshaped when the chest or lapel tires. A cheaply fused front can bubble after heat, steam and repeated dry cleaning. Pads and sleeve head rolls can flatten over the years and be renewed by a tailor, and a worn lining can be replaced entirely, which is why a well-built jacket can be kept in service for decades.

How can you tell what is inside a jacket?

What to ask a tailor about the inside of a jacket

Once you know the layers, you can feel the difference between jackets in a minute. To see how a tailor builds them into a coat, read how a bespoke suit is made, and for the other quality checks, see our 10 signs of a high-quality suit.

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