Interfacings are used to provide shape, stability, strength, durability, and structure in garments, accessories, and household furnishings. In garments they are used in areas such as collars, lapels, necklines, cuffs, waistbands, hems, armholes, buttonholes, and in zipper areas. In collars, necklines and cuffs, they help to provide shape, and in the buttonhole and zipper areas they help to provide strength and durability.
When it comes to accessories, interfacings are used in purses, hats, and belts. In curtains they help to improve the drape and can also help to reduce wrinkling after washing. Furthermore, interfacings can be used in costumes to help provide shape.
Interfacing is usually applied in between two layers of fabric and firmly attached to one layer of the fabric. This way it will remain in place and will not be seen when the garment is worn.
There are many different types of interfacing such as wovens, non-wovens, knits, fusible and non-fusible, also known as sew-ins. Fusible interfacings can be attached to material with a hot iron. Non-fusibles have to be sewn in. Interfacings also come in different fibers, different weights of light, medium and heavy, and usually come in the colors of white, beige, gray or black. So technically, there’s an interfacing for basically every type of material.
Woven interfacings have a lengthwise and crosswise grain, and must be cut on the same grain as the fabric. Otherwise when the two grains meet, it might distort the fabric and result in an unwanted drape. Woven interfacings are stable and help to increase the durability of the fabric. They are usually used with woven fabrics.
Non-woven interfacings are bonded together. Unlike the woven, these do not have a grain and are not very strong. They are not suitable for using in buttonholes and other areas that need reinforcing.
Knit interfacings have a crosswise stretch, thus making them great for knit fabrics. They usually are lightweight, soft and drape well.
Whether woven, non-woven or knit, all interfacings are available in fusible and non-fusible.
Non-fusible, or sew-in interfacings are pinned or basted to the fabric, then sewn in with the sewing machine. Non-fusibles will not alter the texture or shape of the fabric, and are great for when natural shaping is desired.
You can also get a fusible web that you can use to bond the non-fusible interfacing to the fabric. You can use this in hems, or to temporarily hold appliques and/or patches in place before sewing.
Fusible interfacings have a glue-like coating on one side so that when steam-pressed, it melts and fuses the interfacing to the wrong side of the fabric. All fusible interfacings are different and come with instructions on how to apply them. Make sure to read and follow these instructions as not doing so will reduce the strength of the bond.
Fusibles are quick and easy to apply, but not all fabrics are suitable for fusibles. Some delicate fabrics cannot take the heat, and textured fabrics may lose their texture during the application. So always double check to make sure you don’t ruin your project.
Everyone has their own preference on which interfacing to use for different fabrics. The general rule however, is to use interfacing of the same weight or a bit lighter than that of the fabric. To determine which interfacing to use, simply drape two layers of fabric and the interfacing together to see how well they hang. For collars, lapels, and cuffs you will usually need a stiffer interfacing in order to achieve the desired shape.
For sheer fabrics you might not be able to use an interfacing. However, if you need a reinforcement you can simply use another layer of fabric as an interfacing. That way everything matches and nothing gets distorted. In some cases you might also choose a contrasting color to add more character to the garment.