Interfacing is the 'back stage' of the garment. For everything to look good 'out front' there is a lot of work going on behind the scenes. Interfacing provides support, prevents stretching, and makes your garment look newer longer. Using interfacing takes time and techniques that some stitchers think can be skipped. They overlook that 'fussy stuff' in favor of speed. These fussy steps will take the garment from the Community Theater up to the lights of Broadway.
There are more types of interfacing today than there were a few years ago because there are more types of fabric available to the home sewer. The trick is to combine the right interfacing with the right fabric. Different parts of the garment need different amounts of support. Two layers of a thinner interfacing may work better than one layer of thicker. Some fabrics can not stand the heat required for fusible interfacing. There are fabrics that should be interfaced with another piece of fabric because the color of the interfacing will show through. Using black interfacing on darker garments can keep the interfaced areas looking darker longer. Some decisions are science and some are personal preference.
The first thing to do with interfacing is shrink it. This applies to sew-in and fusible. The yoke on a blouse of mine is bubbled because the interfacing shrank after it was finished. Fabric bubbling indicates interfacing shrinking, interfacing bubbling indicates fabric shrinking. Place the interfacing loosely in the tub. Turn on the hot water and just cover the interfacing. Let it relax in the tub until the water cools. Take it out and wrap with a towel to blot out some of the moisture. Do not wring, squeeze or twist. Then lay it out on a table until dry. After shrinking, gently roll the interfacing around an old wrapping paper core to keep it smooth. A good place to keep a interfacing supply is in a plastic wrapping paper box.
When purchasing interfacing buy a bigger piece than is needed for one project. Write the name of the interfacing on a corner. Then if you find a favorite, you will be able to get more. Purchasing extra interfacings will allow you to have different weights on hand for new projects. If a piece of fusible interfacing is wrinkled, place it resin side down against a Teflon pressing sheet. Press out the wrinkles using as little heat as possible. Let it cool and peel it from the sheet.
Take time to test the fusible interfacing with the fabric. Just holding them together won't give a true feeling for the completed project. With iron-on interfacing the resin will make the bonded piece stiffer than the fabric and interfacing would seem to be when they are just held together. This is because the resin eliminates any movement between the layers. Some fabrics will not work with iron on interfacing due to the type of fiber or the weave. The resin can also change the surface texture of the garment. If it has a loose weave like seersucker the 'bumps' will be flattened by iron-in. Even if the surface texture is not very apparent it is always best to do a test sample. Take a 6 inch square of fabric and a 5 inch square of interfacing. Bond them together and see how they react. They may be too firm or not firm enough.
Four factors are necessary for a bond between fabric and interfacing. They are, heat, steam, pressure and time. The iron must hot enough to melt the resin. Wool is the usual setting but check the manufacturer’s suggestion. Steam is necessary to make the resin liquid. Never soaking wet, a damp press cloth or the iron’s steam is the correct amount. Pressure forces the interfacing and the fabric together. Lower the ironing board and push down very hard, do not move the iron back and forth. It takes time for all of this to happen, 10 to 15 seconds in each spot is required to get a proper fuse. Cooling is as important as heating, let the fabric cool completely before handling. Then check the bond. Try to pull it apart, roll it, fold it, feel it and examine it. Don’t be timid about fusing or the bond won’t hold through the first wash.
Before doing any fusing, lay an old piece of sheet over the board to prevent any resin from sticking to the cover. Lay the fabric,right side down, on the board. Press the fabric with a lot of steam. This warms and prepares the fabric. Position the interfacing, resin side down, on the fabric. Before pressing hover the iron just a half inch above the interfacing, and press the steam button. Steam the entire piece of interfacing. This should prevent any further shrinkage. Starting in the middle press the interfacing to the fabric. Hold the iron in each spot for 15 seconds and press hard. Move to the next area, over lapping a little, and press again. Repeat the process until all areas are fused. Flip the piece over and repeat the pressing on the fabric side. Then let it cool completely before cutting or sewing.
Look inside a top quality purchased ensemble and you will see layers of interfacings and inner stitching that give the garment its shape and style. These techniques can be duplicated at home, if you take the time to set the stage.