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Understanding Interfacing
By Judy Barlup, Unique Techniques

Confused about interfacing? That�s no wonder! There are so many types: fusible and non-fusible; wovens, non-wovens and knits (and now we have weft insertions and warp insertions to further confuse matters); different weights, colors and brands. How are we to decide which one to use with all these factors? The task of selecting interfacing can be simplified when you understand why we use it and some of its characteristics. 

Interfacing is it a third layer of fabric applied between two other layers to provide shape, stability and structure to garments and to enhance durability. It is used in buttonhole areas to keep them from stretching and distortion, in collars and cuffs to add crispness and in facings to give stability. In tailoring, it allows the garment to retain the shape that is built in during the construction process. It can be used for special dramatic effects in costuming. In order to understand interfacing, it is important to look at some of the differences. One of the major characteristics is in the structure of the fiber. 

Woven interfacings are stable. They offer firm support and are available in many weights. 

Knit interfacings are drapeable and soft. They are generally light weight. 

Weft and warp insertion interfacings are knit fabrics with threads woven through them. These interfacings combine the stability of the wovens with the drapeability of the knits. They are available in light to medium weight. 

Non-woven interfacings are made of synthetic fibers. They are neither woven nor knit. (In my opinion, are generally not suitable for quality garments. Use them for craft projects.) Another important characteristic is the method of applications: fusible or non-fusible. Fusible interfacings are easier to stitch, especially when using slippery fabrics. I use fusible interfacing for tailoring. It allows me to shape the fabric with pressing and to use a fusible roll line tape, thus eliminating the hand stitched required in traditional tailoring. Fusible interfacing can save time on the one hand, but on the other hand, they may take longer to apply. They may possibly change the hand of the fabrics. Although I generally don�t have problems with puckering and bubbling with the quality interfacings that are on the market today, there is a chance that this may occur. 

Non-fusibles (also referred to as �sew-ins�) may be softer and less likely to change the hand of the fabric. Goats hair hymo is a non-fusible interfacing that is used in traditional tailoring. In the past, haute couture garments were more likely to use non-fusible interfacing rather than fusible. This is changing as the quality of the fusibles improves. 100% cotton fabric may have residual shrinkage (meaning that it may continue to shrink slightly with each washing). For these fabrics, it is safer to use the non-fusible interfacings. 

Woven interfacings are available as fusibles and non-fusibles. All knit and weft insertion interfacings are fusible. 

The weight of the interfacing is an important consideration and is dependent on the fabric it will be used with, the style of the garment and your personal preference. If an interfacing is too light, it won�t do the job. If it is too heavy, it will change the character of the fabric. For a stand-up mandarin collar, a shirt collar or French cuffs, you would want a firm interfacing. On the same garment, you may want a softer interfacing down the front of the blouse so it isn�t too �boardy.� On a soft jacket with a lot of movement, you would want a lightweight interfacing. For a more structured coat or jacket you might want a heavier weight interfacing. Personal preference is a factor, too. I like my jackets to be more structured and to hang away from my body, so I would select a heavier interfacing. If you want a slimmer fit and the garment to shape to the contours of your body, select a softer interfacing. 

There are special purpose interfacings. �Cool Fuse� describes a category of interfacing that can be applied to delicate fabrics with a cooler iron setting. Nylon tricot comes in 60� widths and is excellent for applying to the complete yardage for underlining when you want to change the character of the fabric (such as giving it more body so you can use it for tailoring or to make linen more wrinkle resistant). Textured Weft is a fusible interfacing that allows you to interface fabric with loft (hand woven, mohair, brocades, corduroy, velvets, etc.) without crushing the nap. Flex Weave is a fusible interfacing that maintains the stretch of the fabric (fabrics with lycra, knits, slinkies, etc). Sheer Magic is a lightweight, sheer fusible that comes in several shades of skin tones for use in see-thru fabrics. (See Lisa Shepard�s article �Invisible Underlayers� in Threads issue #96, Sept 2001.) All of these are manufactured by HTC. 

Note:  The HTC distributor has changes and therefore some of the names of interfacings have also changed.

How do you know which one is the right one? Selection of interfacing is an art, not a science. What is right for you may not be right for the next person, even if you both are using the same fabric and style. You will learn what you like from experience. When you are using a non-fusible interfacing, don�t limit yourself to the interfacing section at the fabric store. Look at the cotton broadcloth, cotton/poly broadcloth, silk organza, etc. This is especially useful if you have a sheer fabric and want a color to blend with it or with your skin tone. 

Always test first. If you are using a non-fusible, you can hold the interfacing between two layers of fabric and drape them over your hand to see how it feels. For a cuff, wrap it around your wrist and see if it gives you the crispness that you want. For a collar, hold it up to your neck. Ask yourself if the interfacing does what you want it to do (provide crispness, drapeability, flexibility, stability)? Does it change the character of the fabric? 

To test fusible interfacings, they have to be applied to the fabric since the heat of the iron and the bonding of the fusible change the felt and weight of the two layers. It is a good idea to have several types of interfacing on hand from which to choose. Test several, then select the one that you think will work best. (Save the sample to help you the next time you make a similar garment. If you find your garment a little to stiff, select a softer or more drapeable interfacing the next time. If it wasn�t firm enough, select a lighter weigh or one with more drape.) 

By pre-treating the fabric and the interfacing, the bubble and puckering can generally be eliminated. For non-fusibles, wash by hand and line dry or put them in the washer and dryer. For fusibles, soak in a basin of hot water (a comfortable temperature to put your hands in) for 30 minutes. Squeeze out excess moisture and hang over the shower rod to dry. (I put an expandable rod over the tub.)

 In cutting the interfacing, don�t bother to trim off any of the seam allowance. Just use the same pattern for the piece you are interfacing. Bulk comes from poor pressing, not from interfacing in the seam allowance. For small pieces, i.e. (collars, cuffs, facings) it may be easier to interfacing the fabric first, then cut the pattern pieces. 

Apply the interfacing by sandwiching the garment piece and interfacing between two press clothes to keep the ironing board and iron clean. Use a flat surface (particle board covered with several layers of wool and several layers of cotton works well). Set the iron at the lowest temperature for steam, apply a lot of pressure and press for 10 seconds. Move the iron a small distance and repeat until you have covered every inch of the interfacing. Do not move until dry. 

In most cases, the above method will work. However. If the interfacing doesn�t adhere well, if it puckers or bubbles, experiment with more steam or less steam, a hotter iron or a cooler iron, a damp press cloth and a dry iron, etc. until you get the bond that you want. If nothing works, resort to a sew-in. With the quality of the fusibles on the market today, this is rarely necessary. 

The best known producer of interfacings is (HTC) but there are other brands available. Check with your local stores to see what they have and what they recommend. Sawyerbrook is an excellent mail order source ( http://www.sawyerbrook.com  ) that provides assistance with your selection. With a bit of knowledge about interfacing and with the help of the store or mail order source, you should have the confidence to �face up to interfacing�.

Judy Barlup
Unique Techniques, Bellevue, WA
email: [email protected]
http://www.uniquetechniques.com 

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