A lining is a secondary layer of fabric, sewn to the inside of your garment used to conceal any unfinished seams, markings, or construction details. A lining can also provide a layer of comfort if the wrong side of your main fabric feels rough against the skin. Having a Interlining will allow you to remove and put on clothing with ease. The most common fabrics used for lining range from silk, polyester, rayon, and acetate. Some designers may even use a contrasting color for their lining as an interesting design feature.
Interlinings are used to provide an additional layer of warmth to finished garments. The interlining can be sewn directly into the construction of the garment or as a separate removable piece. This is usually the case when making coats and certain types of outerwear. Fabrics used for interlinings will differ depending on the desired weight and layer of warmth needed. Common fabrics and materials used for interlinings include fleece, flannel, batting, and other fillings. For heavier winter coats, some designers may even use down feathers, fur, or man-made fillers like Thinsulate that help prevent moisture. Underlining is a layer of fabric used to add body and structure to a lightweight fabric.
Because the underlining acts as a second layer, it should be cut to match each pattern piece, then sewn to the wrong side of your main fabric. It can also provide more opacity if needed for sheer/transparent fabrics. Adding the underling must be done before constructing your garment. When choosing fabric for underlining, make sure that it is lighter than your main fabric. Common fabrics used for underlinings include cotton broadcloth or muslin, cotton batiste, and organza or tulle for heavier fabrics.
A great solution to underlining sheer fabric would be to use self-fabric. Interfacings are generally used for reinforcing the most functional parts of a garment. For example, collars, button plackets, and cuffs are all lined with a layer of fusible or non-fusible interfacing. Fusible interfacings have an adhesive backing that fuses to another fabric when the heat is applied. When using non-fusible or sew-in interfacing, you would apply it to your pattern pieces as you would with underlining. Fusible interfacings can also be used as a stiffener to shape and add body to parts of a garment. Interfacing is available in woven, non-woven, and knit.