How to choose and use Interfacing
If you have never purchased interfacing for dressmaking it can be a rather confusing subject.
Interfacing is an extra layer of fabric applied to the inside of a garment in order to give it some strength and stability. It is normally used on cuffs, collars, shoulder areas and waistbands to add structure and stop the fabric from being floppy.
You can buy interfacing specifically for your fabric and it comes as either iron on or no-iron on. Iron on interfacing is especially good for beginner dressmakers as once ironed into place it doesnt shift about when sewing the layers under your sewing machine. It is suitable for most fabrics made from natural materials, ie cotton and linen. Iron on (or fusible) interfacing is not suitable for any fabrics with a knapp, like velvet, cordurouy or fur because it will crush them. It’s also unsuitable for sequinned fabric, vinyls and metallics because they are not designed to have direct heat applied to them or for lace or scrim because the nature of the open weave fabric means that glue will always seep out through the other side. These fabrics are far more suited to a sew in interfacing as it will not affect the drape nearly as much. Sew in interfacings are only normally used by professional dressmakers, along with linen interfacings that are used by tailors to add structure to coats and jackets.
Once you have decided on sew in or press in interfacing, you need to make a decision on the type. Most popular is a non woven interfacing because it has no grain and is therefore suited to virtually any fabric. However if you are sewing jersey, you will need a stretch fabric so that the garment retains its flexibility. The basic rule is to match the interfacing so that its qualities are almost identical to the fabric that you are working with. Indeed very lightweight summer cottons can get by with another piece of the fabric used as the structure layer. Interfacing also comes in a dark, charcoal shade and a creamy white and again, you need to match the colour, as far as possible to the colour of the cloth you are cutting.
To use iron on interfacing, first do a test on a scrap of fabric to see how it behaves, ie wrinkles, shrinks etc.
Lay the cut fabric wrong side up on an ironing board then place the interfacing shiny side down on top of it. The shiny side has the glue on it. Lay a damp pressing cloth over the top and gently lay on the iron, just using the weight and a pressing action. Don’t move the iron around as this may disturb the layers of fabric. Allow the everything to cool slightly then check to see if it’s adhered by trying to lift a corner. Once in place it is not repositionable so make sure everything is accurate before you start. Always use a wool setting for pressing unless it’s a really lightweight fabric in which case you can turn the iron up a little higher and never skip using a pressing cloth as it diffuses the direct heat and protects the fabric as well as the iron.