Guide: Choosing the Right Interfacing for Garments

The collar sticks out, the neckline stretches out of shape or the waistband loses its form after just a few washes: often the problem isn't the sewing pattern but interfacing that's missing or doesn't suit the fabric. With this guide to interfacing for garments, you'll find it easier to work out what kind of reinforcement your sewing project really needs – and when less support is the better choice.

Interfacing isn't some invisible afterthought. It gives certain areas stability, stops them stretching and makes sure a garment keeps its lovely fit through wearing and washing. At the same time, it changes the handle of a fabric. That's exactly why choosing carefully pays off: interfacing that's too firm can make a drapey viscose stiff, while interfacing that's too light will barely stabilise a shirt collar.

What interfacing is used for in garments

Interfacing reinforces pieces of fabric that take a lot of strain or need to hold a crisp shape. Classic examples are collars, cuffs, button plackets, waistbands, facings and zip areas. Pocket flaps, belts, shoulder areas or the neckline of a dress also often benefit from the right reinforcement.

With stretch fabrics, interfacing has another job too: it can stop a neckline from distorting while you sew. On a jersey top, you don't need to interface the whole neckband. A narrow strip along the seam line is often enough. That way the neckline keeps its shape without losing its comfortable stretch.

You can usually tell from the sewing pattern whether interfacing is needed. It often states which pieces should be reinforced. If there's no mention of it, think about the piece's function: does it need to stand up, stretch very little or withstand a lot of strain? Then interfacing probably makes sense.

The golden rule: interfacing and fabric must work together

Labels such as light, medium or heavy give you a first idea. But what really matters is how the interfacing works with your main fabric. Lay the interfacing under the fabric and feel both layers together. The fabric should keep its typical character – just a little more stable.

A fine, lightweight fusible interfacing works well with cotton poplin, batiste, thin woven fabrics or light blouse fabrics. It gives collars and facings support without adding visible bulk. For shirts, jackets in woven fabric, pocket flaps or sturdier skirts, a medium-weight interfacing is fine. Very firm interfacings are better suited to wide belts, strongly shaped collars or special details. For a softly draping blouse, they're usually too dominant.

For jersey, sweatshirt fabric and other knits, you need a stretch interfacing. It keeps the reinforced area stable without crackling when you put the garment on or blocking the stretch. Make sure the interfacing gives in at least one direction. With very stretchy fabrics, it should move with the fabric accordingly.

Woven fabrics, jersey and drapey fabrics are very different

Woven fabrics such as cotton, linen or poplin usually have little stretch. Classic fusible interfacings work particularly well here. The finer the fabric, the finer the interfacing should be. Testing is especially worthwhile with sheer fabrics: white interfacing can show through, and a coarse texture may be visible from the right side.

Jersey and ribbing call for a stretch version. For necklines, a narrow stay tape or a strip of interfacing cut on the bias can also be the right solution. It stabilises curves without holding the fabric to a straight edge.

Viscose, modal and other soft, drapey fabrics need a delicate touch. Interfacing can be useful here, for example on a facing or button placket. But choose the lightest one possible. With these materials, beautiful drape is often more important than a particularly crisp finish.

Fusible or sew-in interfacing?

For most garment projects, fusible interfacing is the practical choice. It's bonded to the wrong side of the fabric with heat and pressure and won't shift later on. This saves time and makes it easier to sew facings, collars or button plackets accurately.

Sew-in interfacing is a good alternative if your fabric is heat-sensitive, has a very special surface or mustn't be ironed. It can also be the better choice for very bulky fabrics or for designs that are meant to have a deliberately soft finish. It's attached to the fabric before the garment is sewn together, usually by tacking or within the seam allowance.

So the fusible version isn't automatically better. With faux leather, coated fabrics, sequinned fabrics or delicate synthetic fibres, take the material's care and ironing instructions seriously. A small test piece protects you from shiny patches, melted fibres and interfacing that comes away again after the first wash.

How to test the right interfacing before cutting out

A test takes just a few minutes but can save an entire garment. Cut small pieces from your main fabric and from two or three possible interfacings. Fuse each interfacing according to the manufacturer's instructions and let the samples cool completely. Only then will you see how strong the bond really is.

Handle the samples, fold them and, with stretch fabrics, gently pull them apart. If the fabric suddenly feels papery, the interfacing is too firm. If bubbles form or the adhesive coating lifts at the edges, the temperature, pressure or time probably wasn't right. For clothes that get washed often, you can also put a sample through the wash once.

Keep these four points in mind when choosing:

• The reinforced fabric should suit the garment you're planning and not feel stiffer than you want.
• With jersey, the stretch must be preserved, especially at necklines and when pulling the garment on.
• Light-coloured or sheer fabrics need interfacing that stays as unobtrusive as possible.
• The interfacing should cope with the garment's future care, such as machine washing for everyday clothes.

Fusing interfacing properly: press, don't slide

Cut the interfacing to match the pattern piece. For facings and collars, it's usually cut without seam allowance so the seam doesn't end up unnecessarily bulky. Still, always check your sewing pattern's instructions: some construction techniques work differently.

Place the coated side onto the wrong side of the fabric. If you're unsure, feel carefully: the adhesive side often feels slightly rough or dotted. Then cover everything with a damp cloth, if the interfacing calls for it, and press the iron down section by section. Don't slide it. Sliding can distort the fabric, and fine fabrics quickly develop ripples.

The temperature, pressing time and whether to use steam vary depending on the interfacing. So follow the manufacturer's instructions and test first. After fusing, the pieces should lie flat and cool down completely. Only then should you trim them further or sew them together. This allows the adhesive to bond reliably.

Common problems and what causes them

Bubbles often appear when you've pressed for too short a time or with too little pressure. Sometimes, though, the iron is too hot, causing the adhesive to react unevenly. If a corner comes loose, you can carefully fuse it again using baking paper or a pressing cloth.

If a collar turns out board-stiff, the interfacing was usually too firm or the main fabric too light. With a limp collar, it's the other way round – here you can go one step firmer with the interfacing. If you want a really neat result, you can also combine interfacings of different weights in shirt collars: a little more support in the collar stand, a little less in the collar itself. This is especially worthwhile with fine woven fabrics.

Planning interfacing to suit your project

For a children's dress made of cotton, a lightweight interfacing on the facings and button placket is often enough. On a sweatshirt jacket, a stretch interfacing stabilises the zip edge without the jacket puckering there. A blazer or structured jacket, on the other hand, may need several reinforcements on the collar, lapels and front edges.

Interfacing also plays a role in handmade trousers. The waistband, belt loops and sometimes the pocket openings gain stability from it. On a skirt with a shaped waistband, it stops the waistband from folding over. If you're sewing a softly draping summer skirt with an elasticated waist, however, you often don't need any interfacing at all. Not every seam needs reinforcing.

If you're torn between two weights, the lighter option is usually the better choice for garments. It's almost impossible to bring softness back into a piece that's too stiff. For specific projects, a sample piece, a fabric swatch and the pattern instructions help more than a general recommendation. At Die Stoffkönigin, we're happy to advise you if you'd like to match your fabric and interfacing perfectly.

Feel free to give your interfacing a little test seam before starting the actual project. This unassuming scrap of fabric will often show you sooner than any photo whether your collar, neckline or waistband will end up hanging, fitting and feeling exactly the way you want.