I is for Interfacing

I is for 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). If you are using a pattern, it will normally indicate what type of interfacing 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?

Image from So Happy blog http://sohappytosew.blogspot.com/  

Sew-in or fusible interfacing?

Fusible interfacing is by far the easiest to use. It has an adhesive on one side which bonds permanently with the fabric when applied with an iron. It 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. It 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, and 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.

Knit interfacing is made by knitting the fibres together, and so it has an amount of stretch in it. Knit interfacing is especially suitable for use with jerseys and other stretch fabrics as it will stretch with the garment and not hinder it (if you apply woven interfacing to a knit fabric, you reduce the fabric’s stretch properties as the interfacing layer is unable to stretch with the outer fabric layer). It can be quite hard to find online but you can find it here in my shop.

The decision as to whether to buy woven, non-woven or knit interfacing is usually dictated by the pattern and / or type of fabric you are using. As a general rule, non-woven interfacing is suitable for most tasks unless you are sewing with a jersey of stretch fabric in which case knit interfacing is appropriate. You only really need to consider woven interfacing for particularly fine fabrics such as sheers and silks, where a very natural shaping is essential to preserve the qualities of the fabric.

Choosing the weight of the interfacing

The weight of the interfacing should generally be the same as the fabric, or a bit lighter. Generally you should NOT use a heavier weight interfacing than the fabric, as the interfacing will ‘dominate’ the garment and add an unnatural structure to it. So for medium weight fabrics, use medium weight interfacing. For medium weight knit fabrics, use medium weight knit interfacing. As a general rule, if you try and match the properties of the fabric to the properties of the interfacing, you can’t go far wrong – for very sheer or lightweight fabrics, you can even use a second layer of the main fabric as a form of sew-in interfacing!

Colours & Interfacing

Interfacings generally only come in a dark shade (black / charcoal) or a light shade (white / cream). Simply match up the darkness of the interfacing with the shade of the fabric.

Even though it is applied to the inside of a garment, do not use dark interfacing on light fabrics as the dark may show through (and vice versa), especially if the main fabric is loosely woven. The effect is a bit like wearing a white bra with a black top!

How to apply fusible interfacing.

You can find a tutorial on how to apply fusible interfacing here, on the Sewbox blog.

This article was brought to you by Leah Taylor at Sewbox http://www.sewbox.co.uk/. Sewbox is an online sewing boutique for the stylish sewer, stocking Hot Patterns, Colette Patterns, Serendipity Studio, Kwik Sew, John Kaldor fabrics, handmade ceramic buttons, and more – they will be stocking Liberty fabrics including Liberty printed jerseys from September.