Boning is the technique of adding stiffened pieces of material, usually made of polyester, nylon or steel, into a garment to add structure. Boning is commonly used on corsets, wedding dresses or other form-fitting dresses or tops. Boning can be added to a dress that is already finished to achieve a better fit or to prevent a strapless dress from drooping or falling down. The process involves sewing in a fabric casing and slipping in prepurchased bones.
Select the right kind of boning for your dress. Rigilene boning, which is made of polyester, comes in several different weights and is commonly used in formal wear, such as wedding and prom dresses. These bones are lightweight but do not bend easily --- therefore, they are not good for dress designs that go over the hip. Spiral steel bones are heavier but can bend in all directions and conform to the body. Decide which fabrication will work best for your dress design and purchase your bones in an appropriate length.
Position the bones on your dress. If you are working from a commercial pattern, there are probably markings to indicate where the bones should be placed, but try on the dress to make sure the bones will hit you where they should. If you are using your own design, place the bones where they will provide the support and contour you are looking for. Try the dress on and place the bones against your body to see what will work. Mark the position with pins or a fabric pen on the inside of the dress.
Construct casings for the bones. Cut a strip of fabric that is about 1/8 inch wider and about 1/2 inch longer than your bone. Using your sewing machine, stitch both sides and one end of the fabric to the lining of your dress, leaving one end open. Do this before you attach the lining to the dress. If your dress is completed beyond this point, you can hand sew the casing so that the stitches do not show on the outside of the dress. Repeat this process for however many bones you want to incorporate into your dress.
Slide the bones into their casings after the rest of the dress is complete. Hand stitch the open end of the casing so the bone does not slide out.