Stretch Jersey knit

As I added new fusible interfacing products to the Sewbox shop, I got to thinking about how confusing it can be for a beginner sewer when they first buy interfacing. It’s not the most exciting topic, and it can be difficult to find good advice on how to choose, buy and apply interfacing. So I have written this handy guide to interfacing which I hope some will find useful. First I look at what interfacing is, and how to choose types of interfacing; and finally, how to apply fusible interfacing.

What is interfacing?

Interfacing is an additional layer applied to the inside of garments, in certain areas only, to add firmness, shape, structure, and support to areas such as collars, cuffs, waistbands and pockets; and to stabilise areas such as shoulder seams or necklines, which might otherwise hang limply.

Interfacings come in two main types (fusible or sew-in), three main weaves (non-woven, woven and knit), and in different weights (light, medium, heavy weight). It is important to choose the correct type of interfacing for your garment; if you are using a pattern, they will normally indicate if interfacing is required and what type you need.

When you buy interfacing, you need to decide:

• should you buy sew-in or fusible interfacing?
• do you need woven, non-woven or knit interfacing?
• what weight of interfacing should you buy (light weight, medium weight, heavy weight)?
• which colour interfacing is most appropriate?

Sew-in or fusible interfacing

Fusible interfacing is by far the easiest to use, especially for beginners. It has an adhesive on one side which bonds permanently with the fabric when applied with an iron, due to the combination of heat and steam. Fusible interfacing is suitable for most uses, but avoid it for:

• very textured fabrics – the glue won’t bond well to the fabric
• napped fabrics (e.g. velvet / fur) – the pressing needed to bond the adhesive will crush the fabric
• fabrics that are very heat sensitive – e.g. sequins, metallics, vinyl fabrics (the heat can melt or distort the fabric)
• fabrics with a very loose or open weave e.g. lace, mesh (the glue may seap through to the right side of the fabric)

For these types of fabrics, sew-in interfacing is more suitable. Sew-in interfacing is sewn on to the main fabric just like another normal layer of fabric, and is held in place by the stitches. Sew-in interfacing can also result in a more natural shaping and drape as there is less “stiffness” to it.

Whether to use sew-in or fusible interfacing can make subtle changes to the drape of a garment. For most beginner sewing projects, you will be absolutely fine with fusible interfacing; in fact I don’t really recommend using sew-in interfacing until you are really comfortable handling multiple layers of fabric on the sewing machine. Badly sewn in interfacing can really affect the shaping of the garment and give it a poor finish, so unless you’re feeling super confident, and / or your sewing pattern or fabric demands otherwise, stick to the fusible interfacing.

Non-woven, woven or knit interfacing

Non-woven interfacing is made by bonding fibres together and therefore has no grain. You can cut it in any direction, plus it will not ravel, so it is particularly easy to use, and is suitable for most uses (except stretch fabrics – see knit interfacing).

Woven interfacing, like woven fabric, has a lengthwise and crosswise grain. When you cut woven interfacing, be sure to match the grain of the interfacing with the grain of the part of the garment to be interfaced, to make sure the two layers of fabric work together properly. Because of the need to match the grainline, it is less economical than non-woven interfacing, which can be cut in any direction.