Interfacings 101

Posted by Freya Gilbert
on August 29, 2021

Interfacing comes in a wide verity of types, all used for different areas or fabrics

There are 2 main types - fusible or sew-in

There are 3 main weaves - non-woven, woven and knit

There are (usually) 3 different weights - light, medium, heavy weight

It usually comes in black (or charcoal) or white

It is important to choose the correct type of interfacing for your garment; in dressmaking patterns, they will normally state if interfacing is required, how much and what type you need. But it is helpful to know a little more about interfacing to help you select the right type.



How do I Choose the right interfacing for my next project?

Sew-in or fusible interfacing?

Fusible interfacing is easy to use and when applied correctly, produces a great finish. It has an adhesive on one side which bonds permanently with the fabric when heat is applied. Fusible interfacing is suitable for most uses.

However, for some types of fabrics, sew-in interfacing is more suitable. This 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 but it is harder to use for beginners. Make it easier by using a temporary adhesive like 505 spray glue.

You should use non-fusible interfacing for very textured fabrics as the glue won’t bond well to the fabric, napped fabrics like velvet/fur as the pressing needed to activate the adhesive will crush the pile, fabrics that might melt if heat is applied like sequins, metallic, vinyl fabrics and fabrics that are very transparent or have a very loose or open weave like lace or mesh as the glue may seep through to the right side of the fabric.



What's the difference between woven, non-woven or knit interfacing?

Non-woven interfacing is made by bonding fibres together. It has no grain so you can cut it in any direction. It won’t fray. It is important to choose a lighter weight than you think you might need as too heavy a weight can make garments crispy and creasy. Using too much heat or steam can create a bubbly effect on the outer fabric layer it is fused to.

Woven interfacing is a woven fabric which can be very similar to your outer fabric which, once fused onto the outer fabric, strengthens, adds weight and stiffens the fabric whilst retaining the original properties of the fabric. To make sure the two layers of fabric work together properly you must follow the grain of the pattern pieces and treat the interfacing as you would any woven fabric.

Knit interfacing is made by knitting the fibres together, and so it has an amount of stretch in it.  

However, we often prefer to use lightweight non-woven interfacing on jersey garments as this has some stretch but limits the fabric stretching out whilst it is being sewn, adding a little weight without weighing down or changing the overall behaviour of the fabric.

How do I know what weight of interfacing should I buy?

The weight of the interfacing should generally be the same or a bit lighter than the fabric. Using a heavier weight interfacing than the fabric will mean the interfacing adds an unnatural structure to the finished item. In a garment this isn’t usually desirable but in homewares, bags and accessories this can produce some great effects!

As well as matching the interfacing to the weight of the fabric also consider the type of item you’re making.

For instance, you might be making a sweatshirt out of very heavy knit fabric, perhaps you would think you need to use heavy interfacing to match? If you only want to lightly support certain areas without adding bulk, you may only need a lightweight interfacing.  In this situation it's best to do a sample of the interfacing on your fabric and check you're happy with the finished feel and drape of your fabrics.

This blog post was originally included in The Swatch List, issue four

We created The Swatch List Subscription to bring a little of the in-store shopping experience direct to you in the comfort of your own home.  Each month you’ll receive five hand-picked fabrics samples, accompanied by a fact-packed mini magazine full of details about the fabrics, including how to use them, pattern and project suggestions, tips for how to buy fabric online and lots more!