HEAT...MOISTURE...PRESSURE...TIME...are what adhere interfacing to fabric.
First, pre-shrink all interfacings. (I preshrink before the interfacing goes into my sewing room. That way, I can’t confuse preshrunk with not preshrunk!) Be sure to handle your fusible interfacings gently. To pre-shrink, draw a sink full of hot water and immerse the interfacing in the water. Put a plate on top to keep it submerged. Let it sit for 15-20 minutes (until the water cools). Drain and roll it in a towel to remove excess water. If the interfacing is woven, hang to dry over a towel bar with the glue side up. If it’s a knit interfacing, dry it flat. If you hang it, it will just stretch out again.
USE THE RIGHT TOOLS
I recommend a silk organza press cloth. You can see through it, mist through it, steam will penetrate it, and the silk organza will take the highest heat from the iron. To protect your ironing surface, use parchment paper, now available in the grocery store (used to line cookie sheets).
HANDLING FABRIC SHAPES
Many facing pattern pieces have unusual shapes. Once the tissue has been removed from the cut out shape, the fabric shape can 'grow' and lose its original shape. Keep the tissue pinned to the fashion fabric until ready to use.
Now build a 'sandwich' on your ironing surface.
- Parchment paper first, to cover the surface, cut for the longest pattern piece you will be interfacing.
- Then your fashion fabric shape, wrong side up.
- Tissue paper pattern piece laid over the fashion fabric to make sure the fabric is in the exact shape of the pattern. If you mishandle the fabric, or allow it to stretch out of shape, and then you interface it in this condition, the interfacing will keep the distorted shape. It could become very difficult to match the interfaced fabric piece to another part of the garment, or a collar or facing could look crooked when you’re finished.
- Next, remove the pattern tissue and place the interfacing glue side down.
- On top, the silk organza press cloth. Make sure to always face the press cloth with the same side next to the interfacing to keep the sole plate of the iron clean. Have an additional press cloth exclusively for finish-pressing garments. If you use the same press cloth for everything, glue can transfer to the plate of the iron or onto a finished garment. (Write along the edge of one press cloth with a 'Sharpie' pen, “This side up”, “interfacing cloth”.)
- When first testing the heat for the interfacing and the fabric, start with the iron just inside steam range and move the button higher as needed. Begin pressing the “sandwich” in the center and work out toward the edges. Apply pressure for at least 10 seconds in every location, but continue to move the iron until the whole piece is pressed and 10 seconds has been applied to every section. Apply steam as you are pressing. You are PRESSING, not IRONING. Do not slide the iron back and forth over the press cloth. You will push the interfacing and garment out of shape.
Some interfacings and fabrics need a bit more coaxing to adhere to each other. Heat the fashion fabric by steaming and pressing before the interfacing is placed into position. You might try a misting bottle filled with warm water, spritzing the organza pressing cloth through to the 'interfacing sandwich'. You will learn the best way to apply the interfacing in the testing stage. Let the garment shape/interfacing dry completely before moving.
A word about 'Block Interfacing', which is pressing large sections of interfacing and fashion fabric together. Do this only when necessary. It could be helpful if a pattern piece has an intricate cut, or the fabric could twist off grain, or if the fabric ravels very badly.